1 /* 2 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "jvm.h" 27 #include "aot/aotLoader.hpp" 28 #include "classfile/classFileParser.hpp" 29 #include "classfile/classFileStream.hpp" 30 #include "classfile/classLoader.hpp" 31 #include "classfile/classLoaderData.inline.hpp" 32 #include "classfile/classLoaderExt.hpp" 33 #include "classfile/dictionary.hpp" 34 #include "classfile/javaClasses.inline.hpp" 35 #include "classfile/klassFactory.hpp" 36 #include "classfile/loaderConstraints.hpp" 37 #include "classfile/packageEntry.hpp" 38 #include "classfile/placeholders.hpp" 39 #include "classfile/protectionDomainCache.hpp" 40 #include "classfile/resolutionErrors.hpp" 41 #include "classfile/stringTable.hpp" 42 #include "classfile/systemDictionary.hpp" 43 #include "classfile/vmSymbols.hpp" 44 #include "code/codeCache.hpp" 45 #include "compiler/compileBroker.hpp" 46 #include "gc/shared/gcLocker.hpp" 47 #include "gc/shared/gcTraceTime.inline.hpp" 48 #include "interpreter/bytecodeStream.hpp" 49 #include "interpreter/interpreter.hpp" 50 #include "logging/log.hpp" 51 #include "logging/logStream.hpp" 52 #include "memory/filemap.hpp" 53 #include "memory/metaspaceClosure.hpp" 54 #include "memory/oopFactory.hpp" 55 #include "memory/resourceArea.hpp" 56 #include "oops/instanceKlass.hpp" 57 #include "oops/instanceRefKlass.hpp" 58 #include "oops/klass.inline.hpp" 59 #include "oops/methodData.hpp" 60 #include "oops/objArrayKlass.hpp" 61 #include "oops/objArrayOop.inline.hpp" 62 #include "oops/oop.inline.hpp" 63 #include "oops/symbol.hpp" 64 #include "oops/typeArrayKlass.hpp" 65 #include "prims/jvmtiEnvBase.hpp" 66 #include "prims/resolvedMethodTable.hpp" 67 #include "prims/methodHandles.hpp" 68 #include "runtime/arguments.hpp" 69 #include "runtime/arguments_ext.hpp" 70 #include "runtime/biasedLocking.hpp" 71 #include "runtime/fieldType.hpp" 72 #include "runtime/handles.inline.hpp" 73 #include "runtime/java.hpp" 74 #include "runtime/javaCalls.hpp" 75 #include "runtime/mutexLocker.hpp" 76 #include "runtime/orderAccess.inline.hpp" 77 #include "runtime/signature.hpp" 78 #include "services/classLoadingService.hpp" 79 #include "services/diagnosticCommand.hpp" 80 #include "services/threadService.hpp" 81 #include "trace/tracing.hpp" 82 #include "utilities/macros.hpp" 83 #if INCLUDE_CDS 84 #include "classfile/sharedClassUtil.hpp" 85 #include "classfile/systemDictionaryShared.hpp" 86 #endif 87 #if INCLUDE_JVMCI 88 #include "jvmci/jvmciRuntime.hpp" 89 #endif 90 91 PlaceholderTable* SystemDictionary::_placeholders = NULL; 92 Dictionary* SystemDictionary::_shared_dictionary = NULL; 93 LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL; 94 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL; 95 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL; 96 ProtectionDomainCacheTable* SystemDictionary::_pd_cache_table = NULL; 97 98 int SystemDictionary::_number_of_modifications = 0; 99 oop SystemDictionary::_system_loader_lock_obj = NULL; 100 101 InstanceKlass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT] 102 = { NULL /*, NULL...*/ }; 103 104 InstanceKlass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ }; 105 106 oop SystemDictionary::_java_system_loader = NULL; 107 oop SystemDictionary::_java_platform_loader = NULL; 108 109 bool SystemDictionary::_has_checkPackageAccess = false; 110 111 // lazily initialized klass variables 112 InstanceKlass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL; 113 114 // Default ProtectionDomainCacheSize value 115 116 const int defaultProtectionDomainCacheSize = 1009; 117 118 119 // ---------------------------------------------------------------------------- 120 // Java-level SystemLoader and PlatformLoader 121 122 oop SystemDictionary::java_system_loader() { 123 return _java_system_loader; 124 } 125 126 oop SystemDictionary::java_platform_loader() { 127 return _java_platform_loader; 128 } 129 130 void SystemDictionary::compute_java_loaders(TRAPS) { 131 JavaValue result(T_OBJECT); 132 InstanceKlass* class_loader_klass = SystemDictionary::ClassLoader_klass(); 133 JavaCalls::call_static(&result, 134 class_loader_klass, 135 vmSymbols::getSystemClassLoader_name(), 136 vmSymbols::void_classloader_signature(), 137 CHECK); 138 139 _java_system_loader = (oop)result.get_jobject(); 140 141 JavaCalls::call_static(&result, 142 class_loader_klass, 143 vmSymbols::getPlatformClassLoader_name(), 144 vmSymbols::void_classloader_signature(), 145 CHECK); 146 147 _java_platform_loader = (oop)result.get_jobject(); 148 149 CDS_ONLY(SystemDictionaryShared::initialize(CHECK);) 150 } 151 152 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) { 153 if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data(); 154 return ClassLoaderDataGraph::find_or_create(class_loader, THREAD); 155 } 156 157 // ---------------------------------------------------------------------------- 158 // Parallel class loading check 159 160 bool SystemDictionary::is_parallelCapable(Handle class_loader) { 161 if (class_loader.is_null()) return true; 162 if (AlwaysLockClassLoader) return false; 163 return java_lang_ClassLoader::parallelCapable(class_loader()); 164 } 165 // ---------------------------------------------------------------------------- 166 // ParallelDefineClass flag does not apply to bootclass loader 167 bool SystemDictionary::is_parallelDefine(Handle class_loader) { 168 if (class_loader.is_null()) return false; 169 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) { 170 return true; 171 } 172 return false; 173 } 174 175 // Returns true if the passed class loader is the builtin application class loader 176 // or a custom system class loader. A customer system class loader can be 177 // specified via -Djava.system.class.loader. 178 bool SystemDictionary::is_system_class_loader(oop class_loader) { 179 if (class_loader == NULL) { 180 return false; 181 } 182 return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() || 183 class_loader == _java_system_loader); 184 } 185 186 // Returns true if the passed class loader is the platform class loader. 187 bool SystemDictionary::is_platform_class_loader(oop class_loader) { 188 if (class_loader == NULL) { 189 return false; 190 } 191 return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass()); 192 } 193 194 // ---------------------------------------------------------------------------- 195 // Resolving of classes 196 197 // Forwards to resolve_or_null 198 199 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) { 200 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD); 201 if (HAS_PENDING_EXCEPTION || klass == NULL) { 202 // can return a null klass 203 klass = handle_resolution_exception(class_name, throw_error, klass, THREAD); 204 } 205 return klass; 206 } 207 208 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name, 209 bool throw_error, 210 Klass* klass, TRAPS) { 211 if (HAS_PENDING_EXCEPTION) { 212 // If we have a pending exception we forward it to the caller, unless throw_error is true, 213 // in which case we have to check whether the pending exception is a ClassNotFoundException, 214 // and if so convert it to a NoClassDefFoundError 215 // And chain the original ClassNotFoundException 216 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) { 217 ResourceMark rm(THREAD); 218 assert(klass == NULL, "Should not have result with exception pending"); 219 Handle e(THREAD, PENDING_EXCEPTION); 220 CLEAR_PENDING_EXCEPTION; 221 THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e); 222 } else { 223 return NULL; 224 } 225 } 226 // Class not found, throw appropriate error or exception depending on value of throw_error 227 if (klass == NULL) { 228 ResourceMark rm(THREAD); 229 if (throw_error) { 230 THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string()); 231 } else { 232 THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string()); 233 } 234 } 235 return klass; 236 } 237 238 239 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, 240 bool throw_error, TRAPS) 241 { 242 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD); 243 } 244 245 246 // Forwards to resolve_instance_class_or_null 247 248 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) { 249 assert(THREAD->can_call_java(), 250 "can not load classes with compiler thread: class=%s, classloader=%s", 251 class_name->as_C_string(), 252 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string()); 253 if (FieldType::is_array(class_name)) { 254 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD); 255 } else if (FieldType::is_obj(class_name)) { 256 ResourceMark rm(THREAD); 257 // Ignore wrapping L and ;. 258 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1, 259 class_name->utf8_length() - 2, CHECK_NULL); 260 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD); 261 } else { 262 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD); 263 } 264 } 265 266 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) { 267 return resolve_or_null(class_name, Handle(), Handle(), THREAD); 268 } 269 270 // Forwards to resolve_instance_class_or_null 271 272 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name, 273 Handle class_loader, 274 Handle protection_domain, 275 TRAPS) { 276 assert(FieldType::is_array(class_name), "must be array"); 277 Klass* k = NULL; 278 FieldArrayInfo fd; 279 // dimension and object_key in FieldArrayInfo are assigned as a side-effect 280 // of this call 281 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL); 282 if (t == T_OBJECT) { 283 // naked oop "k" is OK here -- we assign back into it 284 k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(), 285 class_loader, 286 protection_domain, 287 CHECK_NULL); 288 if (k != NULL) { 289 k = k->array_klass(fd.dimension(), CHECK_NULL); 290 } 291 } else { 292 k = Universe::typeArrayKlassObj(t); 293 k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL); 294 } 295 return k; 296 } 297 298 299 // Must be called for any super-class or super-interface resolution 300 // during class definition to allow class circularity checking 301 // super-interface callers: 302 // parse_interfaces - for defineClass & jvmtiRedefineClasses 303 // super-class callers: 304 // ClassFileParser - for defineClass & jvmtiRedefineClasses 305 // load_shared_class - while loading a class from shared archive 306 // resolve_instance_class_or_null: 307 // via: handle_parallel_super_load 308 // when resolving a class that has an existing placeholder with 309 // a saved superclass [i.e. a defineClass is currently in progress] 310 // if another thread is trying to resolve the class, it must do 311 // super-class checks on its own thread to catch class circularity 312 // This last call is critical in class circularity checking for cases 313 // where classloading is delegated to different threads and the 314 // classloader lock is released. 315 // Take the case: Base->Super->Base 316 // 1. If thread T1 tries to do a defineClass of class Base 317 // resolve_super_or_fail creates placeholder: T1, Base (super Super) 318 // 2. resolve_instance_class_or_null does not find SD or placeholder for Super 319 // so it tries to load Super 320 // 3. If we load the class internally, or user classloader uses same thread 321 // loadClassFromxxx or defineClass via parseClassFile Super ... 322 // 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base) 323 // 3.3 resolve_instance_class_or_null Base, finds placeholder for Base 324 // 3.4 calls resolve_super_or_fail Base 325 // 3.5 finds T1,Base -> throws class circularity 326 //OR 4. If T2 tries to resolve Super via defineClass Super ... 327 // 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base) 328 // 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super) 329 // 4.3 calls resolve_super_or_fail Super in parallel on own thread T2 330 // 4.4 finds T2, Super -> throws class circularity 331 // Must be called, even if superclass is null, since this is 332 // where the placeholder entry is created which claims this 333 // thread is loading this class/classloader. 334 // Be careful when modifying this code: once you have run 335 // placeholders()->find_and_add(PlaceholderTable::LOAD_SUPER), 336 // you need to find_and_remove it before returning. 337 // So be careful to not exit with a CHECK_ macro betweeen these calls. 338 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name, 339 Symbol* class_name, 340 Handle class_loader, 341 Handle protection_domain, 342 bool is_superclass, 343 TRAPS) { 344 #if INCLUDE_CDS 345 if (DumpSharedSpaces) { 346 // Special processing for CDS dump time. 347 Klass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name, 348 class_name, class_loader, protection_domain, is_superclass, CHECK_NULL); 349 if (k) { 350 return k; 351 } 352 } 353 #endif // INCLUDE_CDS 354 355 // Double-check, if child class is already loaded, just return super-class,interface 356 // Don't add a placedholder if already loaded, i.e. already in appropriate class loader 357 // dictionary. 358 // Make sure there's a placeholder for the *child* before resolving. 359 // Used as a claim that this thread is currently loading superclass/classloader 360 // Used here for ClassCircularity checks and also for heap verification 361 // (every InstanceKlass needs to be in its class loader dictionary or have a placeholder). 362 // Must check ClassCircularity before checking if super class is already loaded. 363 // 364 // We might not already have a placeholder if this child_name was 365 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass); 366 // the name of the class might not be known until the stream is actually 367 // parsed. 368 // Bugs 4643874, 4715493 369 370 ClassLoaderData* loader_data = class_loader_data(class_loader); 371 Dictionary* dictionary = loader_data->dictionary(); 372 unsigned int d_hash = dictionary->compute_hash(child_name); 373 unsigned int p_hash = placeholders()->compute_hash(child_name); 374 int p_index = placeholders()->hash_to_index(p_hash); 375 // can't throw error holding a lock 376 bool child_already_loaded = false; 377 bool throw_circularity_error = false; 378 { 379 MutexLocker mu(SystemDictionary_lock, THREAD); 380 Klass* childk = find_class(d_hash, child_name, dictionary); 381 Klass* quicksuperk; 382 // to support // loading: if child done loading, just return superclass 383 // if class_name, & class_loader don't match: 384 // if initial define, SD update will give LinkageError 385 // if redefine: compare_class_versions will give HIERARCHY_CHANGED 386 // so we don't throw an exception here. 387 // see: nsk redefclass014 & java.lang.instrument Instrument032 388 if ((childk != NULL ) && (is_superclass) && 389 ((quicksuperk = childk->super()) != NULL) && 390 391 ((quicksuperk->name() == class_name) && 392 (quicksuperk->class_loader() == class_loader()))) { 393 return quicksuperk; 394 } else { 395 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data); 396 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) { 397 throw_circularity_error = true; 398 } 399 } 400 if (!throw_circularity_error) { 401 // Be careful not to exit resolve_super 402 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD); 403 } 404 } 405 if (throw_circularity_error) { 406 ResourceMark rm(THREAD); 407 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string()); 408 } 409 410 // java.lang.Object should have been found above 411 assert(class_name != NULL, "null super class for resolving"); 412 // Resolve the super class or interface, check results on return 413 Klass* superk = SystemDictionary::resolve_or_null(class_name, 414 class_loader, 415 protection_domain, 416 THREAD); 417 418 // Clean up of placeholders moved so that each classloadAction registrar self-cleans up 419 // It is no longer necessary to keep the placeholder table alive until update_dictionary 420 // or error. GC used to walk the placeholder table as strong roots. 421 // The instanceKlass is kept alive because the class loader is on the stack, 422 // which keeps the loader_data alive, as well as all instanceKlasses in 423 // the loader_data. parseClassFile adds the instanceKlass to loader_data. 424 { 425 MutexLocker mu(SystemDictionary_lock, THREAD); 426 placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD); 427 SystemDictionary_lock->notify_all(); 428 } 429 if (HAS_PENDING_EXCEPTION || superk == NULL) { 430 // can null superk 431 superk = handle_resolution_exception(class_name, true, superk, THREAD); 432 } 433 434 return superk; 435 } 436 437 void SystemDictionary::validate_protection_domain(InstanceKlass* klass, 438 Handle class_loader, 439 Handle protection_domain, 440 TRAPS) { 441 if(!has_checkPackageAccess()) return; 442 443 // Now we have to call back to java to check if the initating class has access 444 JavaValue result(T_VOID); 445 LogTarget(Debug, protectiondomain) lt; 446 if (lt.is_enabled()) { 447 ResourceMark rm; 448 // Print out trace information 449 LogStream ls(lt); 450 ls.print_cr("Checking package access"); 451 ls.print("class loader: "); class_loader()->print_value_on(&ls); 452 ls.print(" protection domain: "); protection_domain()->print_value_on(&ls); 453 ls.print(" loading: "); klass->print_value_on(&ls); 454 ls.cr(); 455 } 456 457 // This handle and the class_loader handle passed in keeps this class from 458 // being unloaded through several GC points. 459 // The class_loader handle passed in is the initiating loader. 460 Handle mirror(THREAD, klass->java_mirror()); 461 462 InstanceKlass* system_loader = SystemDictionary::ClassLoader_klass(); 463 JavaCalls::call_special(&result, 464 class_loader, 465 system_loader, 466 vmSymbols::checkPackageAccess_name(), 467 vmSymbols::class_protectiondomain_signature(), 468 mirror, 469 protection_domain, 470 THREAD); 471 472 if (HAS_PENDING_EXCEPTION) { 473 log_debug(protectiondomain)("DENIED !!!!!!!!!!!!!!!!!!!!!"); 474 } else { 475 log_debug(protectiondomain)("granted"); 476 } 477 478 if (HAS_PENDING_EXCEPTION) return; 479 480 // If no exception has been thrown, we have validated the protection domain 481 // Insert the protection domain of the initiating class into the set. 482 { 483 ClassLoaderData* loader_data = class_loader_data(class_loader); 484 Dictionary* dictionary = loader_data->dictionary(); 485 486 Symbol* kn = klass->name(); 487 unsigned int d_hash = dictionary->compute_hash(kn); 488 489 MutexLocker mu(SystemDictionary_lock, THREAD); 490 int d_index = dictionary->hash_to_index(d_hash); 491 dictionary->add_protection_domain(d_index, d_hash, klass, 492 protection_domain, THREAD); 493 } 494 } 495 496 // We only get here if this thread finds that another thread 497 // has already claimed the placeholder token for the current operation, 498 // but that other thread either never owned or gave up the 499 // object lock 500 // Waits on SystemDictionary_lock to indicate placeholder table updated 501 // On return, caller must recheck placeholder table state 502 // 503 // We only get here if 504 // 1) custom classLoader, i.e. not bootstrap classloader 505 // 2) custom classLoader has broken the class loader objectLock 506 // so another thread got here in parallel 507 // 508 // lockObject must be held. 509 // Complicated dance due to lock ordering: 510 // Must first release the classloader object lock to 511 // allow initial definer to complete the class definition 512 // and to avoid deadlock 513 // Reclaim classloader lock object with same original recursion count 514 // Must release SystemDictionary_lock after notify, since 515 // class loader lock must be claimed before SystemDictionary_lock 516 // to prevent deadlocks 517 // 518 // The notify allows applications that did an untimed wait() on 519 // the classloader object lock to not hang. 520 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) { 521 assert_lock_strong(SystemDictionary_lock); 522 523 bool calledholdinglock 524 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject); 525 assert(calledholdinglock,"must hold lock for notify"); 526 assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait"); 527 ObjectSynchronizer::notifyall(lockObject, THREAD); 528 intptr_t recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD); 529 SystemDictionary_lock->wait(); 530 SystemDictionary_lock->unlock(); 531 ObjectSynchronizer::reenter(lockObject, recursions, THREAD); 532 SystemDictionary_lock->lock(); 533 } 534 535 // If the class in is in the placeholder table, class loading is in progress 536 // For cases where the application changes threads to load classes, it 537 // is critical to ClassCircularity detection that we try loading 538 // the superclass on the same thread internally, so we do parallel 539 // super class loading here. 540 // This also is critical in cases where the original thread gets stalled 541 // even in non-circularity situations. 542 // Note: must call resolve_super_or_fail even if null super - 543 // to force placeholder entry creation for this class for circularity detection 544 // Caller must check for pending exception 545 // Returns non-null Klass* if other thread has completed load 546 // and we are done, 547 // If return null Klass* and no pending exception, the caller must load the class 548 InstanceKlass* SystemDictionary::handle_parallel_super_load( 549 Symbol* name, Symbol* superclassname, Handle class_loader, 550 Handle protection_domain, Handle lockObject, TRAPS) { 551 552 ClassLoaderData* loader_data = class_loader_data(class_loader); 553 Dictionary* dictionary = loader_data->dictionary(); 554 unsigned int d_hash = dictionary->compute_hash(name); 555 unsigned int p_hash = placeholders()->compute_hash(name); 556 int p_index = placeholders()->hash_to_index(p_hash); 557 558 // superk is not used, resolve_super called for circularity check only 559 // This code is reached in two situations. One if this thread 560 // is loading the same class twice (e.g. ClassCircularity, or 561 // java.lang.instrument). 562 // The second is if another thread started the resolve_super first 563 // and has not yet finished. 564 // In both cases the original caller will clean up the placeholder 565 // entry on error. 566 Klass* superk = SystemDictionary::resolve_super_or_fail(name, 567 superclassname, 568 class_loader, 569 protection_domain, 570 true, 571 CHECK_NULL); 572 573 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete 574 // Serial class loaders and bootstrap classloader do wait for superclass loads 575 if (!class_loader.is_null() && is_parallelCapable(class_loader)) { 576 MutexLocker mu(SystemDictionary_lock, THREAD); 577 // Check if classloading completed while we were loading superclass or waiting 578 return find_class(d_hash, name, dictionary); 579 } 580 581 // must loop to both handle other placeholder updates 582 // and spurious notifications 583 bool super_load_in_progress = true; 584 PlaceholderEntry* placeholder; 585 while (super_load_in_progress) { 586 MutexLocker mu(SystemDictionary_lock, THREAD); 587 // Check if classloading completed while we were loading superclass or waiting 588 InstanceKlass* check = find_class(d_hash, name, dictionary); 589 if (check != NULL) { 590 // Klass is already loaded, so just return it 591 return check; 592 } else { 593 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data); 594 if (placeholder && placeholder->super_load_in_progress() ){ 595 // We only get here if the application has released the 596 // classloader lock when another thread was in the middle of loading a 597 // superclass/superinterface for this class, and now 598 // this thread is also trying to load this class. 599 // To minimize surprises, the first thread that started to 600 // load a class should be the one to complete the loading 601 // with the classfile it initially expected. 602 // This logic has the current thread wait once it has done 603 // all the superclass/superinterface loading it can, until 604 // the original thread completes the class loading or fails 605 // If it completes we will use the resulting InstanceKlass 606 // which we will find below in the systemDictionary. 607 // We also get here for parallel bootstrap classloader 608 if (class_loader.is_null()) { 609 SystemDictionary_lock->wait(); 610 } else { 611 double_lock_wait(lockObject, THREAD); 612 } 613 } else { 614 // If not in SD and not in PH, other thread's load must have failed 615 super_load_in_progress = false; 616 } 617 } 618 } 619 return NULL; 620 } 621 622 static void post_class_load_event(EventClassLoad* event, 623 const InstanceKlass* k, 624 const ClassLoaderData* init_cld) { 625 #if INCLUDE_TRACE 626 assert(event != NULL, "invariant"); 627 assert(k != NULL, "invariant"); 628 if (event->should_commit()) { 629 event->set_loadedClass(k); 630 event->set_definingClassLoader(k->class_loader_data()); 631 event->set_initiatingClassLoader(init_cld); 632 event->commit(); 633 } 634 #endif // INCLUDE_TRACE 635 } 636 637 static void class_define_event(InstanceKlass* k, 638 const ClassLoaderData* def_cld) { 639 #if INCLUDE_TRACE 640 EventClassDefine event; 641 if (event.should_commit()) { 642 event.set_definedClass(k); 643 event.set_definingClassLoader(def_cld); 644 event.commit(); 645 } 646 #endif // INCLUDE_TRACE 647 } 648 649 // Be careful when modifying this code: once you have run 650 // placeholders()->find_and_add(PlaceholderTable::LOAD_INSTANCE), 651 // you need to find_and_remove it before returning. 652 // So be careful to not exit with a CHECK_ macro betweeen these calls. 653 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name, 654 Handle class_loader, 655 Handle protection_domain, 656 TRAPS) { 657 assert(name != NULL && !FieldType::is_array(name) && 658 !FieldType::is_obj(name), "invalid class name"); 659 660 EventClassLoad class_load_start_event; 661 662 HandleMark hm(THREAD); 663 664 // Fix for 4474172; see evaluation for more details 665 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader())); 666 ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL); 667 Dictionary* dictionary = loader_data->dictionary(); 668 unsigned int d_hash = dictionary->compute_hash(name); 669 670 // Do lookup to see if class already exist and the protection domain 671 // has the right access 672 // This call uses find which checks protection domain already matches 673 // All subsequent calls use find_class, and set has_loaded_class so that 674 // before we return a result we call out to java to check for valid protection domain 675 // to allow returning the Klass* and add it to the pd_set if it is valid 676 { 677 Klass* probe = dictionary->find(d_hash, name, protection_domain); 678 if (probe != NULL) return probe; 679 } 680 681 // Non-bootstrap class loaders will call out to class loader and 682 // define via jvm/jni_DefineClass which will acquire the 683 // class loader object lock to protect against multiple threads 684 // defining the class in parallel by accident. 685 // This lock must be acquired here so the waiter will find 686 // any successful result in the SystemDictionary and not attempt 687 // the define. 688 // ParallelCapable Classloaders and the bootstrap classloader 689 // do not acquire lock here. 690 bool DoObjectLock = true; 691 if (is_parallelCapable(class_loader)) { 692 DoObjectLock = false; 693 } 694 695 unsigned int p_hash = placeholders()->compute_hash(name); 696 int p_index = placeholders()->hash_to_index(p_hash); 697 698 // Class is not in SystemDictionary so we have to do loading. 699 // Make sure we are synchronized on the class loader before we proceed 700 Handle lockObject = compute_loader_lock_object(class_loader, THREAD); 701 check_loader_lock_contention(lockObject, THREAD); 702 ObjectLocker ol(lockObject, THREAD, DoObjectLock); 703 704 // Check again (after locking) if class already exist in SystemDictionary 705 bool class_has_been_loaded = false; 706 bool super_load_in_progress = false; 707 bool havesupername = false; 708 InstanceKlass* k = NULL; 709 PlaceholderEntry* placeholder; 710 Symbol* superclassname = NULL; 711 712 { 713 MutexLocker mu(SystemDictionary_lock, THREAD); 714 InstanceKlass* check = find_class(d_hash, name, dictionary); 715 if (check != NULL) { 716 // Klass is already loaded, so just return it 717 class_has_been_loaded = true; 718 k = check; 719 } else { 720 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data); 721 if (placeholder && placeholder->super_load_in_progress()) { 722 super_load_in_progress = true; 723 if (placeholder->havesupername() == true) { 724 superclassname = placeholder->supername(); 725 havesupername = true; 726 } 727 } 728 } 729 } 730 731 // If the class is in the placeholder table, class loading is in progress 732 if (super_load_in_progress && havesupername==true) { 733 k = handle_parallel_super_load(name, 734 superclassname, 735 class_loader, 736 protection_domain, 737 lockObject, THREAD); 738 if (HAS_PENDING_EXCEPTION) { 739 return NULL; 740 } 741 if (k != NULL) { 742 class_has_been_loaded = true; 743 } 744 } 745 746 bool throw_circularity_error = false; 747 if (!class_has_been_loaded) { 748 bool load_instance_added = false; 749 750 // add placeholder entry to record loading instance class 751 // Five cases: 752 // All cases need to prevent modifying bootclasssearchpath 753 // in parallel with a classload of same classname 754 // Redefineclasses uses existence of the placeholder for the duration 755 // of the class load to prevent concurrent redefinition of not completely 756 // defined classes. 757 // case 1. traditional classloaders that rely on the classloader object lock 758 // - no other need for LOAD_INSTANCE 759 // case 2. traditional classloaders that break the classloader object lock 760 // as a deadlock workaround. Detection of this case requires that 761 // this check is done while holding the classloader object lock, 762 // and that lock is still held when calling classloader's loadClass. 763 // For these classloaders, we ensure that the first requestor 764 // completes the load and other requestors wait for completion. 765 // case 3. Bootstrap classloader - don't own objectLocker 766 // This classloader supports parallelism at the classloader level, 767 // but only allows a single load of a class/classloader pair. 768 // No performance benefit and no deadlock issues. 769 // case 4. parallelCapable user level classloaders - without objectLocker 770 // Allow parallel classloading of a class/classloader pair 771 772 { 773 MutexLocker mu(SystemDictionary_lock, THREAD); 774 if (class_loader.is_null() || !is_parallelCapable(class_loader)) { 775 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data); 776 if (oldprobe) { 777 // only need check_seen_thread once, not on each loop 778 // 6341374 java/lang/Instrument with -Xcomp 779 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) { 780 throw_circularity_error = true; 781 } else { 782 // case 1: traditional: should never see load_in_progress. 783 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) { 784 785 // case 3: bootstrap classloader: prevent futile classloading, 786 // wait on first requestor 787 if (class_loader.is_null()) { 788 SystemDictionary_lock->wait(); 789 } else { 790 // case 2: traditional with broken classloader lock. wait on first 791 // requestor. 792 double_lock_wait(lockObject, THREAD); 793 } 794 // Check if classloading completed while we were waiting 795 InstanceKlass* check = find_class(d_hash, name, dictionary); 796 if (check != NULL) { 797 // Klass is already loaded, so just return it 798 k = check; 799 class_has_been_loaded = true; 800 } 801 // check if other thread failed to load and cleaned up 802 oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data); 803 } 804 } 805 } 806 } 807 // All cases: add LOAD_INSTANCE holding SystemDictionary_lock 808 // case 4: parallelCapable: allow competing threads to try 809 // LOAD_INSTANCE in parallel 810 811 if (!throw_circularity_error && !class_has_been_loaded) { 812 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD); 813 load_instance_added = true; 814 // For class loaders that do not acquire the classloader object lock, 815 // if they did not catch another thread holding LOAD_INSTANCE, 816 // need a check analogous to the acquire ObjectLocker/find_class 817 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL 818 // one final check if the load has already completed 819 // class loaders holding the ObjectLock shouldn't find the class here 820 InstanceKlass* check = find_class(d_hash, name, dictionary); 821 if (check != NULL) { 822 // Klass is already loaded, so return it after checking/adding protection domain 823 k = check; 824 class_has_been_loaded = true; 825 } 826 } 827 } 828 829 // must throw error outside of owning lock 830 if (throw_circularity_error) { 831 assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup"); 832 ResourceMark rm(THREAD); 833 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string()); 834 } 835 836 if (!class_has_been_loaded) { 837 838 // Do actual loading 839 k = load_instance_class(name, class_loader, THREAD); 840 841 // If everything was OK (no exceptions, no null return value), and 842 // class_loader is NOT the defining loader, do a little more bookkeeping. 843 if (!HAS_PENDING_EXCEPTION && k != NULL && 844 k->class_loader() != class_loader()) { 845 846 check_constraints(d_hash, k, class_loader, false, THREAD); 847 848 // Need to check for a PENDING_EXCEPTION again; check_constraints 849 // can throw and doesn't use the CHECK macro. 850 if (!HAS_PENDING_EXCEPTION) { 851 { // Grabbing the Compile_lock prevents systemDictionary updates 852 // during compilations. 853 MutexLocker mu(Compile_lock, THREAD); 854 update_dictionary(d_hash, p_index, p_hash, 855 k, class_loader, THREAD); 856 } 857 858 if (JvmtiExport::should_post_class_load()) { 859 Thread *thread = THREAD; 860 assert(thread->is_Java_thread(), "thread->is_Java_thread()"); 861 JvmtiExport::post_class_load((JavaThread *) thread, k); 862 } 863 } 864 } 865 } // load_instance_class 866 867 if (load_instance_added == true) { 868 // clean up placeholder entries for LOAD_INSTANCE success or error 869 // This brackets the SystemDictionary updates for both defining 870 // and initiating loaders 871 MutexLocker mu(SystemDictionary_lock, THREAD); 872 placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD); 873 SystemDictionary_lock->notify_all(); 874 } 875 } 876 877 if (HAS_PENDING_EXCEPTION || k == NULL) { 878 return NULL; 879 } 880 881 post_class_load_event(&class_load_start_event, k, loader_data); 882 883 #ifdef ASSERT 884 { 885 ClassLoaderData* loader_data = k->class_loader_data(); 886 MutexLocker mu(SystemDictionary_lock, THREAD); 887 Klass* kk = find_class(name, loader_data); 888 assert(kk == k, "should be present in dictionary"); 889 } 890 #endif 891 892 // return if the protection domain in NULL 893 if (protection_domain() == NULL) return k; 894 895 // Check the protection domain has the right access 896 if (dictionary->is_valid_protection_domain(d_hash, name, 897 protection_domain)) { 898 return k; 899 } 900 901 // Verify protection domain. If it fails an exception is thrown 902 validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL); 903 904 return k; 905 } 906 907 908 // This routine does not lock the system dictionary. 909 // 910 // Since readers don't hold a lock, we must make sure that system 911 // dictionary entries are only removed at a safepoint (when only one 912 // thread is running), and are added to in a safe way (all links must 913 // be updated in an MT-safe manner). 914 // 915 // Callers should be aware that an entry could be added just after 916 // _dictionary->bucket(index) is read here, so the caller will not see 917 // the new entry. 918 919 Klass* SystemDictionary::find(Symbol* class_name, 920 Handle class_loader, 921 Handle protection_domain, 922 TRAPS) { 923 924 // The result of this call should be consistent with the result 925 // of the call to resolve_instance_class_or_null(). 926 // See evaluation 6790209 and 4474172 for more details. 927 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader())); 928 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader()); 929 930 if (loader_data == NULL) { 931 // If the ClassLoaderData has not been setup, 932 // then the class loader has no entries in the dictionary. 933 return NULL; 934 } 935 936 Dictionary* dictionary = loader_data->dictionary(); 937 unsigned int d_hash = dictionary->compute_hash(class_name); 938 return dictionary->find(d_hash, class_name, 939 protection_domain); 940 } 941 942 943 // Look for a loaded instance or array klass by name. Do not do any loading. 944 // return NULL in case of error. 945 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name, 946 Handle class_loader, 947 Handle protection_domain, 948 TRAPS) { 949 Klass* k = NULL; 950 assert(class_name != NULL, "class name must be non NULL"); 951 952 if (FieldType::is_array(class_name)) { 953 // The name refers to an array. Parse the name. 954 // dimension and object_key in FieldArrayInfo are assigned as a 955 // side-effect of this call 956 FieldArrayInfo fd; 957 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL)); 958 if (t != T_OBJECT) { 959 k = Universe::typeArrayKlassObj(t); 960 } else { 961 k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD); 962 } 963 if (k != NULL) { 964 k = k->array_klass_or_null(fd.dimension()); 965 } 966 } else { 967 k = find(class_name, class_loader, protection_domain, THREAD); 968 } 969 return k; 970 } 971 972 // Note: this method is much like resolve_from_stream, but 973 // does not publish the classes via the SystemDictionary. 974 // Handles unsafe_DefineAnonymousClass and redefineclasses 975 // RedefinedClasses do not add to the class hierarchy 976 InstanceKlass* SystemDictionary::parse_stream(Symbol* class_name, 977 Handle class_loader, 978 Handle protection_domain, 979 ClassFileStream* st, 980 const InstanceKlass* host_klass, 981 GrowableArray<Handle>* cp_patches, 982 TRAPS) { 983 984 EventClassLoad class_load_start_event; 985 986 ClassLoaderData* loader_data; 987 if (host_klass != NULL) { 988 // Create a new CLD for anonymous class, that uses the same class loader 989 // as the host_klass 990 guarantee(host_klass->class_loader() == class_loader(), "should be the same"); 991 loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL); 992 } else { 993 loader_data = ClassLoaderData::class_loader_data(class_loader()); 994 } 995 996 assert(st != NULL, "invariant"); 997 assert(st->need_verify(), "invariant"); 998 999 // Parse stream and create a klass. 1000 // Note that we do this even though this klass might 1001 // already be present in the SystemDictionary, otherwise we would not 1002 // throw potential ClassFormatErrors. 1003 1004 InstanceKlass* k = KlassFactory::create_from_stream(st, 1005 class_name, 1006 loader_data, 1007 protection_domain, 1008 host_klass, 1009 cp_patches, 1010 CHECK_NULL); 1011 1012 if (host_klass != NULL && k != NULL) { 1013 // If it's anonymous, initialize it now, since nobody else will. 1014 1015 { 1016 MutexLocker mu_r(Compile_lock, THREAD); 1017 1018 // Add to class hierarchy, initialize vtables, and do possible 1019 // deoptimizations. 1020 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block 1021 1022 // But, do not add to dictionary. 1023 1024 // compiled code dependencies need to be validated anyway 1025 notice_modification(); 1026 } 1027 1028 // Rewrite and patch constant pool here. 1029 k->link_class(CHECK_NULL); 1030 if (cp_patches != NULL) { 1031 k->constants()->patch_resolved_references(cp_patches); 1032 } 1033 k->eager_initialize(CHECK_NULL); 1034 1035 // notify jvmti 1036 if (JvmtiExport::should_post_class_load()) { 1037 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()"); 1038 JvmtiExport::post_class_load((JavaThread *) THREAD, k); 1039 } 1040 1041 post_class_load_event(&class_load_start_event, k, loader_data); 1042 } 1043 assert(host_klass != NULL || NULL == cp_patches, 1044 "cp_patches only found with host_klass"); 1045 1046 return k; 1047 } 1048 1049 // Add a klass to the system from a stream (called by jni_DefineClass and 1050 // JVM_DefineClass). 1051 // Note: class_name can be NULL. In that case we do not know the name of 1052 // the class until we have parsed the stream. 1053 1054 InstanceKlass* SystemDictionary::resolve_from_stream(Symbol* class_name, 1055 Handle class_loader, 1056 Handle protection_domain, 1057 ClassFileStream* st, 1058 TRAPS) { 1059 1060 HandleMark hm(THREAD); 1061 1062 // Classloaders that support parallelism, e.g. bootstrap classloader, 1063 // do not acquire lock here 1064 bool DoObjectLock = true; 1065 if (is_parallelCapable(class_loader)) { 1066 DoObjectLock = false; 1067 } 1068 1069 ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL); 1070 1071 // Make sure we are synchronized on the class loader before we proceed 1072 Handle lockObject = compute_loader_lock_object(class_loader, THREAD); 1073 check_loader_lock_contention(lockObject, THREAD); 1074 ObjectLocker ol(lockObject, THREAD, DoObjectLock); 1075 1076 assert(st != NULL, "invariant"); 1077 1078 // Parse the stream and create a klass. 1079 // Note that we do this even though this klass might 1080 // already be present in the SystemDictionary, otherwise we would not 1081 // throw potential ClassFormatErrors. 1082 InstanceKlass* k = NULL; 1083 1084 #if INCLUDE_CDS 1085 if (!DumpSharedSpaces) { 1086 k = SystemDictionaryShared::lookup_from_stream(class_name, 1087 class_loader, 1088 protection_domain, 1089 st, 1090 CHECK_NULL); 1091 } 1092 #endif 1093 1094 if (k == NULL) { 1095 if (st->buffer() == NULL) { 1096 return NULL; 1097 } 1098 k = KlassFactory::create_from_stream(st, 1099 class_name, 1100 loader_data, 1101 protection_domain, 1102 NULL, // host_klass 1103 NULL, // cp_patches 1104 CHECK_NULL); 1105 } 1106 1107 assert(k != NULL, "no klass created"); 1108 Symbol* h_name = k->name(); 1109 assert(class_name == NULL || class_name == h_name, "name mismatch"); 1110 1111 // Add class just loaded 1112 // If a class loader supports parallel classloading handle parallel define requests 1113 // find_or_define_instance_class may return a different InstanceKlass 1114 if (is_parallelCapable(class_loader)) { 1115 InstanceKlass* defined_k = find_or_define_instance_class(h_name, class_loader, k, THREAD); 1116 if (!HAS_PENDING_EXCEPTION && defined_k != k) { 1117 // If a parallel capable class loader already defined this class, register 'k' for cleanup. 1118 assert(defined_k != NULL, "Should have a klass if there's no exception"); 1119 loader_data->add_to_deallocate_list(k); 1120 k = defined_k; 1121 } 1122 } else { 1123 define_instance_class(k, THREAD); 1124 } 1125 1126 // If defining the class throws an exception register 'k' for cleanup. 1127 if (HAS_PENDING_EXCEPTION) { 1128 assert(k != NULL, "Must have an instance klass here!"); 1129 loader_data->add_to_deallocate_list(k); 1130 return NULL; 1131 } 1132 1133 // Make sure we have an entry in the SystemDictionary on success 1134 debug_only( { 1135 MutexLocker mu(SystemDictionary_lock, THREAD); 1136 1137 Klass* check = find_class(h_name, k->class_loader_data()); 1138 assert(check == k, "should be present in the dictionary"); 1139 } ); 1140 1141 return k; 1142 } 1143 1144 #if INCLUDE_CDS 1145 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length, 1146 int number_of_entries) { 1147 assert(length == _shared_dictionary_size * sizeof(HashtableBucket<mtClass>), 1148 "bad shared dictionary size."); 1149 _shared_dictionary = new Dictionary(ClassLoaderData::the_null_class_loader_data(), 1150 _shared_dictionary_size, t, number_of_entries); 1151 } 1152 1153 1154 // If there is a shared dictionary, then find the entry for the 1155 // given shared system class, if any. 1156 1157 InstanceKlass* SystemDictionary::find_shared_class(Symbol* class_name) { 1158 if (shared_dictionary() != NULL) { 1159 unsigned int d_hash = shared_dictionary()->compute_hash(class_name); 1160 int d_index = shared_dictionary()->hash_to_index(d_hash); 1161 1162 return shared_dictionary()->find_shared_class(d_index, d_hash, class_name); 1163 } else { 1164 return NULL; 1165 } 1166 } 1167 1168 1169 // Load a class from the shared spaces (found through the shared system 1170 // dictionary). Force the superclass and all interfaces to be loaded. 1171 // Update the class definition to include sibling classes and no 1172 // subclasses (yet). [Classes in the shared space are not part of the 1173 // object hierarchy until loaded.] 1174 1175 InstanceKlass* SystemDictionary::load_shared_class( 1176 Symbol* class_name, Handle class_loader, TRAPS) { 1177 InstanceKlass* ik = find_shared_class(class_name); 1178 // Make sure we only return the boot class for the NULL classloader. 1179 if (ik != NULL && 1180 ik->is_shared_boot_class() && class_loader.is_null()) { 1181 Handle protection_domain; 1182 return load_shared_class(ik, class_loader, protection_domain, THREAD); 1183 } 1184 return NULL; 1185 } 1186 1187 // Check if a shared class can be loaded by the specific classloader: 1188 // 1189 // NULL classloader: 1190 // - Module class from "modules" jimage. ModuleEntry must be defined in the classloader. 1191 // - Class from -Xbootclasspath/a. The class has no defined PackageEntry, or must 1192 // be defined in an unnamed module. 1193 bool SystemDictionary::is_shared_class_visible(Symbol* class_name, 1194 InstanceKlass* ik, 1195 Handle class_loader, TRAPS) { 1196 assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(), 1197 "Cannot use sharing if java.base is patched"); 1198 ResourceMark rm; 1199 int path_index = ik->shared_classpath_index(); 1200 ClassLoaderData* loader_data = class_loader_data(class_loader); 1201 if (path_index < 0) { 1202 // path_index < 0 indicates that the class is intended for a custom loader 1203 // and should not be loaded by boot/platform/app loaders 1204 if (loader_data->is_builtin_class_loader_data()) { 1205 return false; 1206 } else { 1207 return true; 1208 } 1209 } 1210 SharedClassPathEntry* ent = 1211 (SharedClassPathEntry*)FileMapInfo::shared_classpath(path_index); 1212 if (!Universe::is_module_initialized()) { 1213 assert(ent != NULL && ent->is_modules_image(), 1214 "Loading non-bootstrap classes before the module system is initialized"); 1215 assert(class_loader.is_null(), "sanity"); 1216 return true; 1217 } 1218 // Get the pkg_entry from the classloader 1219 TempNewSymbol pkg_name = NULL; 1220 PackageEntry* pkg_entry = NULL; 1221 ModuleEntry* mod_entry = NULL; 1222 const char* pkg_string = NULL; 1223 pkg_name = InstanceKlass::package_from_name(class_name, CHECK_false); 1224 if (pkg_name != NULL) { 1225 pkg_string = pkg_name->as_C_string(); 1226 if (loader_data != NULL) { 1227 pkg_entry = loader_data->packages()->lookup_only(pkg_name); 1228 } 1229 if (pkg_entry != NULL) { 1230 mod_entry = pkg_entry->module(); 1231 } 1232 } 1233 1234 // If the archived class is from a module that has been patched at runtime, 1235 // the class cannot be loaded from the archive. 1236 if (mod_entry != NULL && mod_entry->is_patched()) { 1237 return false; 1238 } 1239 1240 if (class_loader.is_null()) { 1241 assert(ent != NULL, "Shared class for NULL classloader must have valid SharedClassPathEntry"); 1242 // The NULL classloader can load archived class originated from the 1243 // "modules" jimage and the -Xbootclasspath/a. For class from the 1244 // "modules" jimage, the PackageEntry/ModuleEntry must be defined 1245 // by the NULL classloader. 1246 if (mod_entry != NULL) { 1247 // PackageEntry/ModuleEntry is found in the classloader. Check if the 1248 // ModuleEntry's location agrees with the archived class' origination. 1249 if (ent->is_modules_image() && mod_entry->location()->starts_with("jrt:")) { 1250 return true; // Module class from the "module" jimage 1251 } 1252 } 1253 1254 // If the archived class is not from the "module" jimage, the class can be 1255 // loaded by the NULL classloader if 1256 // 1257 // 1. the class is from the unamed package 1258 // 2. or, the class is not from a module defined in the NULL classloader 1259 // 3. or, the class is from an unamed module 1260 if (!ent->is_modules_image() && ik->is_shared_boot_class()) { 1261 // the class is from the -Xbootclasspath/a 1262 if (pkg_string == NULL || 1263 pkg_entry == NULL || 1264 pkg_entry->in_unnamed_module()) { 1265 assert(mod_entry == NULL || 1266 mod_entry == loader_data->unnamed_module(), 1267 "the unnamed module is not defined in the classloader"); 1268 return true; 1269 } 1270 } 1271 return false; 1272 } else { 1273 bool res = SystemDictionaryShared::is_shared_class_visible_for_classloader( 1274 ik, class_loader, pkg_string, pkg_name, 1275 pkg_entry, mod_entry, CHECK_(false)); 1276 return res; 1277 } 1278 } 1279 1280 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik, 1281 Handle class_loader, 1282 Handle protection_domain, TRAPS) { 1283 1284 if (ik != NULL) { 1285 Symbol* class_name = ik->name(); 1286 1287 bool visible = is_shared_class_visible( 1288 class_name, ik, class_loader, CHECK_NULL); 1289 if (!visible) { 1290 return NULL; 1291 } 1292 1293 // Resolve the superclass and interfaces. They must be the same 1294 // as in dump time, because the layout of <ik> depends on 1295 // the specific layout of ik->super() and ik->local_interfaces(). 1296 // 1297 // If unexpected superclass or interfaces are found, we cannot 1298 // load <ik> from the shared archive. 1299 1300 if (ik->super() != NULL) { 1301 Symbol* cn = ik->super()->name(); 1302 Klass *s = resolve_super_or_fail(class_name, cn, 1303 class_loader, protection_domain, true, CHECK_NULL); 1304 if (s != ik->super()) { 1305 // The dynamically resolved super class is not the same as the one we used during dump time, 1306 // so we cannot use ik. 1307 return NULL; 1308 } else { 1309 assert(s->is_shared(), "must be"); 1310 } 1311 } 1312 1313 Array<Klass*>* interfaces = ik->local_interfaces(); 1314 int num_interfaces = interfaces->length(); 1315 for (int index = 0; index < num_interfaces; index++) { 1316 Klass* k = interfaces->at(index); 1317 Symbol* name = k->name(); 1318 Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_NULL); 1319 if (k != i) { 1320 // The dynamically resolved interface class is not the same as the one we used during dump time, 1321 // so we cannot use ik. 1322 return NULL; 1323 } else { 1324 assert(i->is_shared(), "must be"); 1325 } 1326 } 1327 1328 InstanceKlass* new_ik = KlassFactory::check_shared_class_file_load_hook( 1329 ik, class_name, class_loader, protection_domain, CHECK_NULL); 1330 if (new_ik != NULL) { 1331 // The class is changed by CFLH. Return the new class. The shared class is 1332 // not used. 1333 return new_ik; 1334 } 1335 1336 // Adjust methods to recover missing data. They need addresses for 1337 // interpreter entry points and their default native method address 1338 // must be reset. 1339 1340 // Updating methods must be done under a lock so multiple 1341 // threads don't update these in parallel 1342 // 1343 // Shared classes are all currently loaded by either the bootstrap or 1344 // internal parallel class loaders, so this will never cause a deadlock 1345 // on a custom class loader lock. 1346 1347 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader()); 1348 { 1349 HandleMark hm(THREAD); 1350 Handle lockObject = compute_loader_lock_object(class_loader, THREAD); 1351 check_loader_lock_contention(lockObject, THREAD); 1352 ObjectLocker ol(lockObject, THREAD, true); 1353 // prohibited package check assumes all classes loaded from archive call 1354 // restore_unshareable_info which calls ik->set_package() 1355 ik->restore_unshareable_info(loader_data, protection_domain, CHECK_NULL); 1356 } 1357 1358 ik->print_class_load_logging(loader_data, NULL, NULL); 1359 1360 // For boot loader, ensure that GetSystemPackage knows that a class in this 1361 // package was loaded. 1362 if (class_loader.is_null()) { 1363 int path_index = ik->shared_classpath_index(); 1364 ResourceMark rm; 1365 ClassLoader::add_package(ik->name()->as_C_string(), path_index, THREAD); 1366 } 1367 1368 if (DumpLoadedClassList != NULL && classlist_file->is_open()) { 1369 // Only dump the classes that can be stored into CDS archive 1370 if (SystemDictionaryShared::is_sharing_possible(loader_data)) { 1371 ResourceMark rm(THREAD); 1372 classlist_file->print_cr("%s", ik->name()->as_C_string()); 1373 classlist_file->flush(); 1374 } 1375 } 1376 1377 // notify a class loaded from shared object 1378 ClassLoadingService::notify_class_loaded(ik, true /* shared class */); 1379 } 1380 1381 ik->set_has_passed_fingerprint_check(false); 1382 if (UseAOT && ik->supers_have_passed_fingerprint_checks()) { 1383 uint64_t aot_fp = AOTLoader::get_saved_fingerprint(ik); 1384 uint64_t cds_fp = ik->get_stored_fingerprint(); 1385 if (aot_fp != 0 && aot_fp == cds_fp) { 1386 // This class matches with a class saved in an AOT library 1387 ik->set_has_passed_fingerprint_check(true); 1388 } else { 1389 ResourceMark rm; 1390 log_info(class, fingerprint)("%s : expected = " PTR64_FORMAT " actual = " PTR64_FORMAT, ik->external_name(), aot_fp, cds_fp); 1391 } 1392 } 1393 return ik; 1394 } 1395 1396 void SystemDictionary::clear_invoke_method_table() { 1397 SymbolPropertyEntry* spe = NULL; 1398 for (int index = 0; index < _invoke_method_table->table_size(); index++) { 1399 SymbolPropertyEntry* p = _invoke_method_table->bucket(index); 1400 while (p != NULL) { 1401 spe = p; 1402 p = p->next(); 1403 _invoke_method_table->free_entry(spe); 1404 } 1405 } 1406 } 1407 #endif // INCLUDE_CDS 1408 1409 InstanceKlass* SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) { 1410 1411 if (class_loader.is_null()) { 1412 ResourceMark rm; 1413 PackageEntry* pkg_entry = NULL; 1414 bool search_only_bootloader_append = false; 1415 ClassLoaderData *loader_data = class_loader_data(class_loader); 1416 1417 // Find the package in the boot loader's package entry table. 1418 TempNewSymbol pkg_name = InstanceKlass::package_from_name(class_name, CHECK_NULL); 1419 if (pkg_name != NULL) { 1420 pkg_entry = loader_data->packages()->lookup_only(pkg_name); 1421 } 1422 1423 // Prior to attempting to load the class, enforce the boot loader's 1424 // visibility boundaries. 1425 if (!Universe::is_module_initialized()) { 1426 // During bootstrapping, prior to module initialization, any 1427 // class attempting to be loaded must be checked against the 1428 // java.base packages in the boot loader's PackageEntryTable. 1429 // No class outside of java.base is allowed to be loaded during 1430 // this bootstrapping window. 1431 if (pkg_entry == NULL || pkg_entry->in_unnamed_module()) { 1432 // Class is either in the unnamed package or in 1433 // a named package within the unnamed module. Either 1434 // case is outside of java.base, do not attempt to 1435 // load the class post java.base definition. If 1436 // java.base has not been defined, let the class load 1437 // and its package will be checked later by 1438 // ModuleEntryTable::verify_javabase_packages. 1439 if (ModuleEntryTable::javabase_defined()) { 1440 return NULL; 1441 } 1442 } else { 1443 // Check that the class' package is defined within java.base. 1444 ModuleEntry* mod_entry = pkg_entry->module(); 1445 Symbol* mod_entry_name = mod_entry->name(); 1446 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) { 1447 return NULL; 1448 } 1449 } 1450 } else { 1451 // After the module system has been initialized, check if the class' 1452 // package is in a module defined to the boot loader. 1453 if (pkg_name == NULL || pkg_entry == NULL || pkg_entry->in_unnamed_module()) { 1454 // Class is either in the unnamed package, in a named package 1455 // within a module not defined to the boot loader or in a 1456 // a named package within the unnamed module. In all cases, 1457 // limit visibility to search for the class only in the boot 1458 // loader's append path. 1459 search_only_bootloader_append = true; 1460 } 1461 } 1462 1463 // Prior to bootstrapping's module initialization, never load a class outside 1464 // of the boot loader's module path 1465 assert(Universe::is_module_initialized() || 1466 !search_only_bootloader_append, 1467 "Attempt to load a class outside of boot loader's module path"); 1468 1469 // Search the shared system dictionary for classes preloaded into the 1470 // shared spaces. 1471 InstanceKlass* k = NULL; 1472 { 1473 #if INCLUDE_CDS 1474 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time()); 1475 k = load_shared_class(class_name, class_loader, THREAD); 1476 #endif 1477 } 1478 1479 if (k == NULL) { 1480 // Use VM class loader 1481 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time()); 1482 k = ClassLoader::load_class(class_name, search_only_bootloader_append, CHECK_NULL); 1483 } 1484 1485 // find_or_define_instance_class may return a different InstanceKlass 1486 if (k != NULL) { 1487 InstanceKlass* defined_k = 1488 find_or_define_instance_class(class_name, class_loader, k, THREAD); 1489 if (!HAS_PENDING_EXCEPTION && defined_k != k) { 1490 // If a parallel capable class loader already defined this class, register 'k' for cleanup. 1491 assert(defined_k != NULL, "Should have a klass if there's no exception"); 1492 loader_data->add_to_deallocate_list(k); 1493 k = defined_k; 1494 } else if (HAS_PENDING_EXCEPTION) { 1495 loader_data->add_to_deallocate_list(k); 1496 return NULL; 1497 } 1498 } 1499 return k; 1500 } else { 1501 // Use user specified class loader to load class. Call loadClass operation on class_loader. 1502 ResourceMark rm(THREAD); 1503 1504 assert(THREAD->is_Java_thread(), "must be a JavaThread"); 1505 JavaThread* jt = (JavaThread*) THREAD; 1506 1507 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(), 1508 ClassLoader::perf_app_classload_selftime(), 1509 ClassLoader::perf_app_classload_count(), 1510 jt->get_thread_stat()->perf_recursion_counts_addr(), 1511 jt->get_thread_stat()->perf_timers_addr(), 1512 PerfClassTraceTime::CLASS_LOAD); 1513 1514 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_NULL); 1515 // Translate to external class name format, i.e., convert '/' chars to '.' 1516 Handle string = java_lang_String::externalize_classname(s, CHECK_NULL); 1517 1518 JavaValue result(T_OBJECT); 1519 1520 InstanceKlass* spec_klass = SystemDictionary::ClassLoader_klass(); 1521 1522 // Call public unsynchronized loadClass(String) directly for all class loaders. 1523 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will 1524 // acquire a class-name based lock rather than the class loader object lock. 1525 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean). 1526 JavaCalls::call_virtual(&result, 1527 class_loader, 1528 spec_klass, 1529 vmSymbols::loadClass_name(), 1530 vmSymbols::string_class_signature(), 1531 string, 1532 CHECK_NULL); 1533 1534 assert(result.get_type() == T_OBJECT, "just checking"); 1535 oop obj = (oop) result.get_jobject(); 1536 1537 // Primitive classes return null since forName() can not be 1538 // used to obtain any of the Class objects representing primitives or void 1539 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) { 1540 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj)); 1541 // For user defined Java class loaders, check that the name returned is 1542 // the same as that requested. This check is done for the bootstrap 1543 // loader when parsing the class file. 1544 if (class_name == k->name()) { 1545 return k; 1546 } 1547 } 1548 // Class is not found or has the wrong name, return NULL 1549 return NULL; 1550 } 1551 } 1552 1553 void SystemDictionary::define_instance_class(InstanceKlass* k, TRAPS) { 1554 1555 HandleMark hm(THREAD); 1556 ClassLoaderData* loader_data = k->class_loader_data(); 1557 Handle class_loader_h(THREAD, loader_data->class_loader()); 1558 1559 // for bootstrap and other parallel classloaders don't acquire lock, 1560 // use placeholder token 1561 // If a parallelCapable class loader calls define_instance_class instead of 1562 // find_or_define_instance_class to get here, we have a timing 1563 // hole with systemDictionary updates and check_constraints 1564 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) { 1565 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, 1566 compute_loader_lock_object(class_loader_h, THREAD)), 1567 "define called without lock"); 1568 } 1569 1570 // Check class-loading constraints. Throw exception if violation is detected. 1571 // Grabs and releases SystemDictionary_lock 1572 // The check_constraints/find_class call and update_dictionary sequence 1573 // must be "atomic" for a specific class/classloader pair so we never 1574 // define two different instanceKlasses for that class/classloader pair. 1575 // Existing classloaders will call define_instance_class with the 1576 // classloader lock held 1577 // Parallel classloaders will call find_or_define_instance_class 1578 // which will require a token to perform the define class 1579 Symbol* name_h = k->name(); 1580 Dictionary* dictionary = loader_data->dictionary(); 1581 unsigned int d_hash = dictionary->compute_hash(name_h); 1582 check_constraints(d_hash, k, class_loader_h, true, CHECK); 1583 1584 // Register class just loaded with class loader (placed in Vector) 1585 // Note we do this before updating the dictionary, as this can 1586 // fail with an OutOfMemoryError (if it does, we will *not* put this 1587 // class in the dictionary and will not update the class hierarchy). 1588 // JVMTI FollowReferences needs to find the classes this way. 1589 if (k->class_loader() != NULL) { 1590 methodHandle m(THREAD, Universe::loader_addClass_method()); 1591 JavaValue result(T_VOID); 1592 JavaCallArguments args(class_loader_h); 1593 args.push_oop(Handle(THREAD, k->java_mirror())); 1594 JavaCalls::call(&result, m, &args, CHECK); 1595 } 1596 1597 // Add the new class. We need recompile lock during update of CHA. 1598 { 1599 unsigned int p_hash = placeholders()->compute_hash(name_h); 1600 int p_index = placeholders()->hash_to_index(p_hash); 1601 1602 MutexLocker mu_r(Compile_lock, THREAD); 1603 1604 // Add to class hierarchy, initialize vtables, and do possible 1605 // deoptimizations. 1606 add_to_hierarchy(k, CHECK); // No exception, but can block 1607 1608 // Add to systemDictionary - so other classes can see it. 1609 // Grabs and releases SystemDictionary_lock 1610 update_dictionary(d_hash, p_index, p_hash, 1611 k, class_loader_h, THREAD); 1612 } 1613 k->eager_initialize(THREAD); 1614 1615 // notify jvmti 1616 if (JvmtiExport::should_post_class_load()) { 1617 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()"); 1618 JvmtiExport::post_class_load((JavaThread *) THREAD, k); 1619 1620 } 1621 class_define_event(k, loader_data); 1622 } 1623 1624 // Support parallel classloading 1625 // All parallel class loaders, including bootstrap classloader 1626 // lock a placeholder entry for this class/class_loader pair 1627 // to allow parallel defines of different classes for this class loader 1628 // With AllowParallelDefine flag==true, in case they do not synchronize around 1629 // FindLoadedClass/DefineClass, calls, we check for parallel 1630 // loading for them, wait if a defineClass is in progress 1631 // and return the initial requestor's results 1632 // This flag does not apply to the bootstrap classloader. 1633 // With AllowParallelDefine flag==false, call through to define_instance_class 1634 // which will throw LinkageError: duplicate class definition. 1635 // False is the requested default. 1636 // For better performance, the class loaders should synchronize 1637 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they 1638 // potentially waste time reading and parsing the bytestream. 1639 // Note: VM callers should ensure consistency of k/class_name,class_loader 1640 // Be careful when modifying this code: once you have run 1641 // placeholders()->find_and_add(PlaceholderTable::DEFINE_CLASS), 1642 // you need to find_and_remove it before returning. 1643 // So be careful to not exit with a CHECK_ macro betweeen these calls. 1644 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, 1645 InstanceKlass* k, TRAPS) { 1646 1647 Symbol* name_h = k->name(); // passed in class_name may be null 1648 ClassLoaderData* loader_data = class_loader_data(class_loader); 1649 Dictionary* dictionary = loader_data->dictionary(); 1650 1651 unsigned int d_hash = dictionary->compute_hash(name_h); 1652 1653 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS 1654 unsigned int p_hash = placeholders()->compute_hash(name_h); 1655 int p_index = placeholders()->hash_to_index(p_hash); 1656 PlaceholderEntry* probe; 1657 1658 { 1659 MutexLocker mu(SystemDictionary_lock, THREAD); 1660 // First check if class already defined 1661 if (is_parallelDefine(class_loader)) { 1662 InstanceKlass* check = find_class(d_hash, name_h, dictionary); 1663 if (check != NULL) { 1664 return check; 1665 } 1666 } 1667 1668 // Acquire define token for this class/classloader 1669 probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD); 1670 // Wait if another thread defining in parallel 1671 // All threads wait - even those that will throw duplicate class: otherwise 1672 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails 1673 // if other thread has not finished updating dictionary 1674 while (probe->definer() != NULL) { 1675 SystemDictionary_lock->wait(); 1676 } 1677 // Only special cases allow parallel defines and can use other thread's results 1678 // Other cases fall through, and may run into duplicate defines 1679 // caught by finding an entry in the SystemDictionary 1680 if (is_parallelDefine(class_loader) && (probe->instance_klass() != NULL)) { 1681 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD); 1682 SystemDictionary_lock->notify_all(); 1683 #ifdef ASSERT 1684 InstanceKlass* check = find_class(d_hash, name_h, dictionary); 1685 assert(check != NULL, "definer missed recording success"); 1686 #endif 1687 return probe->instance_klass(); 1688 } else { 1689 // This thread will define the class (even if earlier thread tried and had an error) 1690 probe->set_definer(THREAD); 1691 } 1692 } 1693 1694 define_instance_class(k, THREAD); 1695 1696 Handle linkage_exception = Handle(); // null handle 1697 1698 // definer must notify any waiting threads 1699 { 1700 MutexLocker mu(SystemDictionary_lock, THREAD); 1701 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data); 1702 assert(probe != NULL, "DEFINE_CLASS placeholder lost?"); 1703 if (probe != NULL) { 1704 if (HAS_PENDING_EXCEPTION) { 1705 linkage_exception = Handle(THREAD,PENDING_EXCEPTION); 1706 CLEAR_PENDING_EXCEPTION; 1707 } else { 1708 probe->set_instance_klass(k); 1709 } 1710 probe->set_definer(NULL); 1711 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD); 1712 SystemDictionary_lock->notify_all(); 1713 } 1714 } 1715 1716 // Can't throw exception while holding lock due to rank ordering 1717 if (linkage_exception() != NULL) { 1718 THROW_OOP_(linkage_exception(), NULL); // throws exception and returns 1719 } 1720 1721 return k; 1722 } 1723 1724 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) { 1725 // If class_loader is NULL we synchronize on _system_loader_lock_obj 1726 if (class_loader.is_null()) { 1727 return Handle(THREAD, _system_loader_lock_obj); 1728 } else { 1729 return class_loader; 1730 } 1731 } 1732 1733 // This method is added to check how often we have to wait to grab loader 1734 // lock. The results are being recorded in the performance counters defined in 1735 // ClassLoader::_sync_systemLoaderLockContentionRate and 1736 // ClassLoader::_sync_nonSystemLoaderLockConteionRate. 1737 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) { 1738 if (!UsePerfData) { 1739 return; 1740 } 1741 1742 assert(!loader_lock.is_null(), "NULL lock object"); 1743 1744 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock) 1745 == ObjectSynchronizer::owner_other) { 1746 // contention will likely happen, so increment the corresponding 1747 // contention counter. 1748 if (loader_lock() == _system_loader_lock_obj) { 1749 ClassLoader::sync_systemLoaderLockContentionRate()->inc(); 1750 } else { 1751 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc(); 1752 } 1753 } 1754 } 1755 1756 // ---------------------------------------------------------------------------- 1757 // Lookup 1758 1759 InstanceKlass* SystemDictionary::find_class(unsigned int hash, 1760 Symbol* class_name, 1761 Dictionary* dictionary) { 1762 assert_locked_or_safepoint(SystemDictionary_lock); 1763 int index = dictionary->hash_to_index(hash); 1764 return dictionary->find_class(index, hash, class_name); 1765 } 1766 1767 1768 // Basic find on classes in the midst of being loaded 1769 Symbol* SystemDictionary::find_placeholder(Symbol* class_name, 1770 ClassLoaderData* loader_data) { 1771 assert_locked_or_safepoint(SystemDictionary_lock); 1772 unsigned int p_hash = placeholders()->compute_hash(class_name); 1773 int p_index = placeholders()->hash_to_index(p_hash); 1774 return placeholders()->find_entry(p_index, p_hash, class_name, loader_data); 1775 } 1776 1777 1778 // Used for assertions and verification only 1779 // Precalculating the hash and index is an optimization because there are many lookups 1780 // before adding the class. 1781 InstanceKlass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) { 1782 assert_locked_or_safepoint(SystemDictionary_lock); 1783 #ifndef ASSERT 1784 guarantee(VerifyBeforeGC || 1785 VerifyDuringGC || 1786 VerifyBeforeExit || 1787 VerifyDuringStartup || 1788 VerifyAfterGC, "too expensive"); 1789 #endif 1790 1791 Dictionary* dictionary = loader_data->dictionary(); 1792 unsigned int d_hash = dictionary->compute_hash(class_name); 1793 return find_class(d_hash, class_name, dictionary); 1794 } 1795 1796 1797 // ---------------------------------------------------------------------------- 1798 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock 1799 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in 1800 // before a new class is used. 1801 1802 void SystemDictionary::add_to_hierarchy(InstanceKlass* k, TRAPS) { 1803 assert(k != NULL, "just checking"); 1804 assert_locked_or_safepoint(Compile_lock); 1805 1806 // Link into hierachy. Make sure the vtables are initialized before linking into 1807 k->append_to_sibling_list(); // add to superklass/sibling list 1808 k->process_interfaces(THREAD); // handle all "implements" declarations 1809 k->set_init_state(InstanceKlass::loaded); 1810 // Now flush all code that depended on old class hierarchy. 1811 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97) 1812 // Also, first reinitialize vtable because it may have gotten out of synch 1813 // while the new class wasn't connected to the class hierarchy. 1814 CodeCache::flush_dependents_on(k); 1815 } 1816 1817 // ---------------------------------------------------------------------------- 1818 // GC support 1819 1820 void SystemDictionary::always_strong_oops_do(OopClosure* blk) { 1821 roots_oops_do(blk, NULL); 1822 } 1823 1824 1825 #ifdef ASSERT 1826 class VerifySDReachableAndLiveClosure : public OopClosure { 1827 private: 1828 BoolObjectClosure* _is_alive; 1829 1830 template <class T> void do_oop_work(T* p) { 1831 oop obj = oopDesc::load_decode_heap_oop(p); 1832 guarantee(_is_alive->do_object_b(obj), "Oop in protection domain cache table must be live"); 1833 } 1834 1835 public: 1836 VerifySDReachableAndLiveClosure(BoolObjectClosure* is_alive) : OopClosure(), _is_alive(is_alive) { } 1837 1838 virtual void do_oop(oop* p) { do_oop_work(p); } 1839 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 1840 }; 1841 #endif 1842 1843 // Assumes classes in the SystemDictionary are only unloaded at a safepoint 1844 // Note: anonymous classes are not in the SD. 1845 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive, 1846 GCTimer* gc_timer, 1847 bool do_cleaning) { 1848 1849 1850 bool unloading_occurred; 1851 { 1852 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer); 1853 1854 // First, mark for unload all ClassLoaderData referencing a dead class loader. 1855 unloading_occurred = ClassLoaderDataGraph::do_unloading(is_alive, 1856 do_cleaning); 1857 } 1858 1859 if (unloading_occurred) { 1860 GCTraceTime(Debug, gc, phases) t("Dictionary", gc_timer); 1861 constraints()->purge_loader_constraints(); 1862 resolution_errors()->purge_resolution_errors(); 1863 } 1864 1865 { 1866 GCTraceTime(Debug, gc, phases) t("ProtectionDomainCacheTable", gc_timer); 1867 // Oops referenced by the protection domain cache table may get unreachable independently 1868 // of the class loader (eg. cached protection domain oops). So we need to 1869 // explicitly unlink them here. 1870 _pd_cache_table->unlink(is_alive); 1871 1872 #ifdef ASSERT 1873 VerifySDReachableAndLiveClosure cl(is_alive); 1874 _pd_cache_table->oops_do(&cl); 1875 #endif 1876 } 1877 1878 if (do_cleaning) { 1879 GCTraceTime(Debug, gc, phases) t("ResolvedMethodTable", gc_timer); 1880 ResolvedMethodTable::unlink(is_alive); 1881 } 1882 1883 return unloading_occurred; 1884 } 1885 1886 void SystemDictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) { 1887 strong->do_oop(&_java_system_loader); 1888 strong->do_oop(&_java_platform_loader); 1889 strong->do_oop(&_system_loader_lock_obj); 1890 CDS_ONLY(SystemDictionaryShared::roots_oops_do(strong);) 1891 1892 // Do strong roots marking if the closures are the same. 1893 if (strong == weak || !ClassUnloading) { 1894 // Only the protection domain oops contain references into the heap. Iterate 1895 // over all of them. 1896 _pd_cache_table->oops_do(strong); 1897 } else { 1898 if (weak != NULL) { 1899 _pd_cache_table->oops_do(weak); 1900 } 1901 } 1902 1903 // Visit extra methods 1904 invoke_method_table()->oops_do(strong); 1905 1906 if (weak != NULL) { 1907 ResolvedMethodTable::oops_do(weak); 1908 } 1909 } 1910 1911 void SystemDictionary::oops_do(OopClosure* f) { 1912 f->do_oop(&_java_system_loader); 1913 f->do_oop(&_java_platform_loader); 1914 f->do_oop(&_system_loader_lock_obj); 1915 CDS_ONLY(SystemDictionaryShared::oops_do(f);) 1916 1917 // Only the protection domain oops contain references into the heap. Iterate 1918 // over all of them. 1919 _pd_cache_table->oops_do(f); 1920 1921 // Visit extra methods 1922 invoke_method_table()->oops_do(f); 1923 1924 ResolvedMethodTable::oops_do(f); 1925 } 1926 1927 // CDS: scan and relocate all classes in the system dictionary. 1928 void SystemDictionary::classes_do(MetaspaceClosure* it) { 1929 ClassLoaderData::the_null_class_loader_data()->dictionary()->classes_do(it); 1930 } 1931 1932 // CDS: scan and relocate all classes referenced by _well_known_klasses[]. 1933 void SystemDictionary::well_known_klasses_do(MetaspaceClosure* it) { 1934 for (int id = FIRST_WKID; id < WKID_LIMIT; id++) { 1935 it->push(well_known_klass_addr((WKID)id)); 1936 } 1937 } 1938 1939 void SystemDictionary::methods_do(void f(Method*)) { 1940 // Walk methods in loaded classes 1941 ClassLoaderDataGraph::methods_do(f); 1942 // Walk method handle intrinsics 1943 invoke_method_table()->methods_do(f); 1944 } 1945 1946 class RemoveClassesClosure : public CLDClosure { 1947 public: 1948 void do_cld(ClassLoaderData* cld) { 1949 if (cld->is_system_class_loader_data() || cld->is_platform_class_loader_data()) { 1950 cld->dictionary()->remove_classes_in_error_state(); 1951 } 1952 } 1953 }; 1954 1955 void SystemDictionary::remove_classes_in_error_state() { 1956 ClassLoaderData::the_null_class_loader_data()->dictionary()->remove_classes_in_error_state(); 1957 RemoveClassesClosure rcc; 1958 ClassLoaderDataGraph::cld_do(&rcc); 1959 } 1960 1961 // ---------------------------------------------------------------------------- 1962 // Lazily load klasses 1963 1964 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) { 1965 // if multiple threads calling this function, only one thread will load 1966 // the class. The other threads will find the loaded version once the 1967 // class is loaded. 1968 Klass* aos = _abstract_ownable_synchronizer_klass; 1969 if (aos == NULL) { 1970 Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK); 1971 // Force a fence to prevent any read before the write completes 1972 OrderAccess::fence(); 1973 _abstract_ownable_synchronizer_klass = InstanceKlass::cast(k); 1974 } 1975 } 1976 1977 // ---------------------------------------------------------------------------- 1978 // Initialization 1979 1980 void SystemDictionary::initialize(TRAPS) { 1981 // Allocate arrays 1982 _placeholders = new PlaceholderTable(_placeholder_table_size); 1983 _number_of_modifications = 0; 1984 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size); 1985 _resolution_errors = new ResolutionErrorTable(_resolution_error_size); 1986 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size); 1987 _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize); 1988 1989 // Allocate private object used as system class loader lock 1990 _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK); 1991 // Initialize basic classes 1992 initialize_preloaded_classes(CHECK); 1993 } 1994 1995 // Compact table of directions on the initialization of klasses: 1996 static const short wk_init_info[] = { 1997 #define WK_KLASS_INIT_INFO(name, symbol, option) \ 1998 ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \ 1999 << SystemDictionary::CEIL_LG_OPTION_LIMIT) \ 2000 | (int)SystemDictionary::option ), 2001 WK_KLASSES_DO(WK_KLASS_INIT_INFO) 2002 #undef WK_KLASS_INIT_INFO 2003 0 2004 }; 2005 2006 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) { 2007 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob"); 2008 int info = wk_init_info[id - FIRST_WKID]; 2009 int sid = (info >> CEIL_LG_OPTION_LIMIT); 2010 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid); 2011 InstanceKlass** klassp = &_well_known_klasses[id]; 2012 2013 bool must_load; 2014 #if INCLUDE_JVMCI 2015 if (EnableJVMCI) { 2016 // If JVMCI is enabled we require its classes to be found. 2017 must_load = (init_opt < SystemDictionary::Opt) || (init_opt == SystemDictionary::Jvmci); 2018 } else 2019 #endif 2020 { 2021 must_load = (init_opt < SystemDictionary::Opt); 2022 } 2023 2024 if ((*klassp) == NULL) { 2025 Klass* k; 2026 if (must_load) { 2027 k = resolve_or_fail(symbol, true, CHECK_0); // load required class 2028 } else { 2029 k = resolve_or_null(symbol, CHECK_0); // load optional klass 2030 } 2031 (*klassp) = (k == NULL) ? NULL : InstanceKlass::cast(k); 2032 } 2033 return ((*klassp) != NULL); 2034 } 2035 2036 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) { 2037 assert((int)start_id <= (int)limit_id, "IDs are out of order!"); 2038 for (int id = (int)start_id; id < (int)limit_id; id++) { 2039 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob"); 2040 int info = wk_init_info[id - FIRST_WKID]; 2041 int sid = (info >> CEIL_LG_OPTION_LIMIT); 2042 int opt = (info & right_n_bits(CEIL_LG_OPTION_LIMIT)); 2043 2044 initialize_wk_klass((WKID)id, opt, CHECK); 2045 } 2046 2047 // move the starting value forward to the limit: 2048 start_id = limit_id; 2049 } 2050 2051 void SystemDictionary::initialize_preloaded_classes(TRAPS) { 2052 assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once"); 2053 2054 // Create the ModuleEntry for java.base. This call needs to be done here, 2055 // after vmSymbols::initialize() is called but before any classes are pre-loaded. 2056 ClassLoader::classLoader_init2(CHECK); 2057 2058 // Preload commonly used klasses 2059 WKID scan = FIRST_WKID; 2060 // first do Object, then String, Class 2061 #if INCLUDE_CDS 2062 if (UseSharedSpaces) { 2063 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK); 2064 // Initialize the constant pool for the Object_class 2065 Object_klass()->constants()->restore_unshareable_info(CHECK); 2066 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK); 2067 } else 2068 #endif 2069 { 2070 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK); 2071 } 2072 2073 // Calculate offsets for String and Class classes since they are loaded and 2074 // can be used after this point. 2075 java_lang_String::compute_offsets(); 2076 java_lang_Class::compute_offsets(); 2077 2078 // Fixup mirrors for classes loaded before java.lang.Class. 2079 // These calls iterate over the objects currently in the perm gen 2080 // so calling them at this point is matters (not before when there 2081 // are fewer objects and not later after there are more objects 2082 // in the perm gen. 2083 Universe::initialize_basic_type_mirrors(CHECK); 2084 Universe::fixup_mirrors(CHECK); 2085 2086 // do a bunch more: 2087 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK); 2088 2089 // Preload ref klasses and set reference types 2090 InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER); 2091 InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass)); 2092 2093 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK); 2094 InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT); 2095 InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK); 2096 InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL); 2097 InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM); 2098 2099 // JSR 292 classes 2100 WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass); 2101 WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass); 2102 initialize_wk_klasses_until(jsr292_group_start, scan, CHECK); 2103 initialize_wk_klasses_through(jsr292_group_end, scan, CHECK); 2104 initialize_wk_klasses_until(NOT_JVMCI(WKID_LIMIT) JVMCI_ONLY(FIRST_JVMCI_WKID), scan, CHECK); 2105 2106 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass); 2107 _box_klasses[T_CHAR] = WK_KLASS(Character_klass); 2108 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass); 2109 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass); 2110 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass); 2111 _box_klasses[T_SHORT] = WK_KLASS(Short_klass); 2112 _box_klasses[T_INT] = WK_KLASS(Integer_klass); 2113 _box_klasses[T_LONG] = WK_KLASS(Long_klass); 2114 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass); 2115 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass); 2116 2117 { // Compute whether we should use checkPackageAccess or NOT 2118 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature()); 2119 _has_checkPackageAccess = (method != NULL); 2120 } 2121 } 2122 2123 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer). 2124 // If so, returns the basic type it holds. If not, returns T_OBJECT. 2125 BasicType SystemDictionary::box_klass_type(Klass* k) { 2126 assert(k != NULL, ""); 2127 for (int i = T_BOOLEAN; i < T_VOID+1; i++) { 2128 if (_box_klasses[i] == k) 2129 return (BasicType)i; 2130 } 2131 return T_OBJECT; 2132 } 2133 2134 // Constraints on class loaders. The details of the algorithm can be 2135 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java 2136 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is 2137 // that the dictionary needs to maintain a set of contraints that 2138 // must be satisfied by all classes in the dictionary. 2139 // if defining is true, then LinkageError if already in dictionary 2140 // if initiating loader, then ok if InstanceKlass matches existing entry 2141 2142 void SystemDictionary::check_constraints(unsigned int d_hash, 2143 InstanceKlass* k, 2144 Handle class_loader, bool defining, 2145 TRAPS) { 2146 const char *linkage_error1 = NULL; 2147 const char *linkage_error2 = NULL; 2148 { 2149 Symbol* name = k->name(); 2150 ClassLoaderData *loader_data = class_loader_data(class_loader); 2151 2152 MutexLocker mu(SystemDictionary_lock, THREAD); 2153 2154 InstanceKlass* check = find_class(d_hash, name, loader_data->dictionary()); 2155 if (check != NULL) { 2156 // if different InstanceKlass - duplicate class definition, 2157 // else - ok, class loaded by a different thread in parallel, 2158 // we should only have found it if it was done loading and ok to use 2159 // dictionary only holds instance classes, placeholders 2160 // also holds array classes 2161 2162 assert(check->is_instance_klass(), "noninstance in systemdictionary"); 2163 if ((defining == true) || (k != check)) { 2164 linkage_error1 = "loader (instance of "; 2165 linkage_error2 = "): attempted duplicate class definition for name: \""; 2166 } else { 2167 return; 2168 } 2169 } 2170 2171 #ifdef ASSERT 2172 Symbol* ph_check = find_placeholder(name, loader_data); 2173 assert(ph_check == NULL || ph_check == name, "invalid symbol"); 2174 #endif 2175 2176 if (linkage_error1 == NULL) { 2177 if (constraints()->check_or_update(k, class_loader, name) == false) { 2178 linkage_error1 = "loader constraint violation: loader (instance of "; 2179 linkage_error2 = ") previously initiated loading for a different type with name \""; 2180 } 2181 } 2182 } 2183 2184 // Throw error now if needed (cannot throw while holding 2185 // SystemDictionary_lock because of rank ordering) 2186 2187 if (linkage_error1) { 2188 ResourceMark rm(THREAD); 2189 const char* class_loader_name = loader_name(class_loader()); 2190 char* type_name = k->name()->as_C_string(); 2191 size_t buflen = strlen(linkage_error1) + strlen(class_loader_name) + 2192 strlen(linkage_error2) + strlen(type_name) + 2; // +2 for '"' and null byte. 2193 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 2194 jio_snprintf(buf, buflen, "%s%s%s%s\"", linkage_error1, class_loader_name, linkage_error2, type_name); 2195 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf); 2196 } 2197 } 2198 2199 2200 // Update class loader data dictionary - done after check_constraint and add_to_hierachy 2201 // have been called. 2202 void SystemDictionary::update_dictionary(unsigned int d_hash, 2203 int p_index, unsigned int p_hash, 2204 InstanceKlass* k, 2205 Handle class_loader, 2206 TRAPS) { 2207 // Compile_lock prevents systemDictionary updates during compilations 2208 assert_locked_or_safepoint(Compile_lock); 2209 Symbol* name = k->name(); 2210 ClassLoaderData *loader_data = class_loader_data(class_loader); 2211 2212 { 2213 MutexLocker mu1(SystemDictionary_lock, THREAD); 2214 2215 // See whether biased locking is enabled and if so set it for this 2216 // klass. 2217 // Note that this must be done past the last potential blocking 2218 // point / safepoint. We enable biased locking lazily using a 2219 // VM_Operation to iterate the SystemDictionary and installing the 2220 // biasable mark word into each InstanceKlass's prototype header. 2221 // To avoid race conditions where we accidentally miss enabling the 2222 // optimization for one class in the process of being added to the 2223 // dictionary, we must not safepoint after the test of 2224 // BiasedLocking::enabled(). 2225 if (UseBiasedLocking && BiasedLocking::enabled()) { 2226 // Set biased locking bit for all loaded classes; it will be 2227 // cleared if revocation occurs too often for this type 2228 // NOTE that we must only do this when the class is initally 2229 // defined, not each time it is referenced from a new class loader 2230 if (k->class_loader() == class_loader()) { 2231 k->set_prototype_header(markOopDesc::biased_locking_prototype()); 2232 } 2233 } 2234 2235 // Make a new dictionary entry. 2236 Dictionary* dictionary = loader_data->dictionary(); 2237 InstanceKlass* sd_check = find_class(d_hash, name, dictionary); 2238 if (sd_check == NULL) { 2239 dictionary->add_klass(d_hash, name, k); 2240 notice_modification(); 2241 } 2242 #ifdef ASSERT 2243 sd_check = find_class(d_hash, name, dictionary); 2244 assert (sd_check != NULL, "should have entry in dictionary"); 2245 // Note: there may be a placeholder entry: for circularity testing 2246 // or for parallel defines 2247 #endif 2248 SystemDictionary_lock->notify_all(); 2249 } 2250 } 2251 2252 2253 // Try to find a class name using the loader constraints. The 2254 // loader constraints might know about a class that isn't fully loaded 2255 // yet and these will be ignored. 2256 Klass* SystemDictionary::find_constrained_instance_or_array_klass( 2257 Symbol* class_name, Handle class_loader, TRAPS) { 2258 2259 // First see if it has been loaded directly. 2260 // Force the protection domain to be null. (This removes protection checks.) 2261 Handle no_protection_domain; 2262 Klass* klass = find_instance_or_array_klass(class_name, class_loader, 2263 no_protection_domain, CHECK_NULL); 2264 if (klass != NULL) 2265 return klass; 2266 2267 // Now look to see if it has been loaded elsewhere, and is subject to 2268 // a loader constraint that would require this loader to return the 2269 // klass that is already loaded. 2270 if (FieldType::is_array(class_name)) { 2271 // For array classes, their Klass*s are not kept in the 2272 // constraint table. The element Klass*s are. 2273 FieldArrayInfo fd; 2274 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL)); 2275 if (t != T_OBJECT) { 2276 klass = Universe::typeArrayKlassObj(t); 2277 } else { 2278 MutexLocker mu(SystemDictionary_lock, THREAD); 2279 klass = constraints()->find_constrained_klass(fd.object_key(), class_loader); 2280 } 2281 // If element class already loaded, allocate array klass 2282 if (klass != NULL) { 2283 klass = klass->array_klass_or_null(fd.dimension()); 2284 } 2285 } else { 2286 MutexLocker mu(SystemDictionary_lock, THREAD); 2287 // Non-array classes are easy: simply check the constraint table. 2288 klass = constraints()->find_constrained_klass(class_name, class_loader); 2289 } 2290 2291 return klass; 2292 } 2293 2294 2295 bool SystemDictionary::add_loader_constraint(Symbol* class_name, 2296 Handle class_loader1, 2297 Handle class_loader2, 2298 Thread* THREAD) { 2299 ClassLoaderData* loader_data1 = class_loader_data(class_loader1); 2300 ClassLoaderData* loader_data2 = class_loader_data(class_loader2); 2301 2302 Symbol* constraint_name = NULL; 2303 if (!FieldType::is_array(class_name)) { 2304 constraint_name = class_name; 2305 } else { 2306 // For array classes, their Klass*s are not kept in the 2307 // constraint table. The element classes are. 2308 FieldArrayInfo fd; 2309 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false)); 2310 // primitive types always pass 2311 if (t != T_OBJECT) { 2312 return true; 2313 } else { 2314 constraint_name = fd.object_key(); 2315 } 2316 } 2317 2318 Dictionary* dictionary1 = loader_data1->dictionary(); 2319 unsigned int d_hash1 = dictionary1->compute_hash(constraint_name); 2320 2321 Dictionary* dictionary2 = loader_data2->dictionary(); 2322 unsigned int d_hash2 = dictionary2->compute_hash(constraint_name); 2323 2324 { 2325 MutexLocker mu_s(SystemDictionary_lock, THREAD); 2326 InstanceKlass* klass1 = find_class(d_hash1, constraint_name, dictionary1); 2327 InstanceKlass* klass2 = find_class(d_hash2, constraint_name, dictionary2); 2328 return constraints()->add_entry(constraint_name, klass1, class_loader1, 2329 klass2, class_loader2); 2330 } 2331 } 2332 2333 // Add entry to resolution error table to record the error when the first 2334 // attempt to resolve a reference to a class has failed. 2335 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which, 2336 Symbol* error, Symbol* message) { 2337 unsigned int hash = resolution_errors()->compute_hash(pool, which); 2338 int index = resolution_errors()->hash_to_index(hash); 2339 { 2340 MutexLocker ml(SystemDictionary_lock, Thread::current()); 2341 resolution_errors()->add_entry(index, hash, pool, which, error, message); 2342 } 2343 } 2344 2345 // Delete a resolution error for RedefineClasses for a constant pool is going away 2346 void SystemDictionary::delete_resolution_error(ConstantPool* pool) { 2347 resolution_errors()->delete_entry(pool); 2348 } 2349 2350 // Lookup resolution error table. Returns error if found, otherwise NULL. 2351 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which, 2352 Symbol** message) { 2353 unsigned int hash = resolution_errors()->compute_hash(pool, which); 2354 int index = resolution_errors()->hash_to_index(hash); 2355 { 2356 MutexLocker ml(SystemDictionary_lock, Thread::current()); 2357 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which); 2358 if (entry != NULL) { 2359 *message = entry->message(); 2360 return entry->error(); 2361 } else { 2362 return NULL; 2363 } 2364 } 2365 } 2366 2367 2368 // Signature constraints ensure that callers and callees agree about 2369 // the meaning of type names in their signatures. This routine is the 2370 // intake for constraints. It collects them from several places: 2371 // 2372 // * LinkResolver::resolve_method (if check_access is true) requires 2373 // that the resolving class (the caller) and the defining class of 2374 // the resolved method (the callee) agree on each type in the 2375 // method's signature. 2376 // 2377 // * LinkResolver::resolve_interface_method performs exactly the same 2378 // checks. 2379 // 2380 // * LinkResolver::resolve_field requires that the constant pool 2381 // attempting to link to a field agree with the field's defining 2382 // class about the type of the field signature. 2383 // 2384 // * klassVtable::initialize_vtable requires that, when a class 2385 // overrides a vtable entry allocated by a superclass, that the 2386 // overriding method (i.e., the callee) agree with the superclass 2387 // on each type in the method's signature. 2388 // 2389 // * klassItable::initialize_itable requires that, when a class fills 2390 // in its itables, for each non-abstract method installed in an 2391 // itable, the method (i.e., the callee) agree with the interface 2392 // on each type in the method's signature. 2393 // 2394 // All those methods have a boolean (check_access, checkconstraints) 2395 // which turns off the checks. This is used from specialized contexts 2396 // such as bootstrapping, dumping, and debugging. 2397 // 2398 // No direct constraint is placed between the class and its 2399 // supertypes. Constraints are only placed along linked relations 2400 // between callers and callees. When a method overrides or implements 2401 // an abstract method in a supertype (superclass or interface), the 2402 // constraints are placed as if the supertype were the caller to the 2403 // overriding method. (This works well, since callers to the 2404 // supertype have already established agreement between themselves and 2405 // the supertype.) As a result of all this, a class can disagree with 2406 // its supertype about the meaning of a type name, as long as that 2407 // class neither calls a relevant method of the supertype, nor is 2408 // called (perhaps via an override) from the supertype. 2409 // 2410 // 2411 // SystemDictionary::check_signature_loaders(sig, l1, l2) 2412 // 2413 // Make sure all class components (including arrays) in the given 2414 // signature will be resolved to the same class in both loaders. 2415 // Returns the name of the type that failed a loader constraint check, or 2416 // NULL if no constraint failed. No exception except OOME is thrown. 2417 // Arrays are not added to the loader constraint table, their elements are. 2418 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature, 2419 Handle loader1, Handle loader2, 2420 bool is_method, TRAPS) { 2421 // Nothing to do if loaders are the same. 2422 if (loader1() == loader2()) { 2423 return NULL; 2424 } 2425 2426 SignatureStream sig_strm(signature, is_method); 2427 while (!sig_strm.is_done()) { 2428 if (sig_strm.is_object()) { 2429 Symbol* sig = sig_strm.as_symbol(CHECK_NULL); 2430 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) { 2431 return sig; 2432 } 2433 } 2434 sig_strm.next(); 2435 } 2436 return NULL; 2437 } 2438 2439 2440 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid, 2441 Symbol* signature, 2442 TRAPS) { 2443 methodHandle empty; 2444 assert(MethodHandles::is_signature_polymorphic(iid) && 2445 MethodHandles::is_signature_polymorphic_intrinsic(iid) && 2446 iid != vmIntrinsics::_invokeGeneric, 2447 "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid)); 2448 2449 unsigned int hash = invoke_method_table()->compute_hash(signature, iid); 2450 int index = invoke_method_table()->hash_to_index(hash); 2451 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid); 2452 methodHandle m; 2453 if (spe == NULL || spe->method() == NULL) { 2454 spe = NULL; 2455 // Must create lots of stuff here, but outside of the SystemDictionary lock. 2456 m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty)); 2457 if (!Arguments::is_interpreter_only()) { 2458 // Generate a compiled form of the MH intrinsic. 2459 AdapterHandlerLibrary::create_native_wrapper(m); 2460 // Check if have the compiled code. 2461 if (!m->has_compiled_code()) { 2462 THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(), 2463 "Out of space in CodeCache for method handle intrinsic", empty); 2464 } 2465 } 2466 // Now grab the lock. We might have to throw away the new method, 2467 // if a racing thread has managed to install one at the same time. 2468 { 2469 MutexLocker ml(SystemDictionary_lock, THREAD); 2470 spe = invoke_method_table()->find_entry(index, hash, signature, iid); 2471 if (spe == NULL) 2472 spe = invoke_method_table()->add_entry(index, hash, signature, iid); 2473 if (spe->method() == NULL) 2474 spe->set_method(m()); 2475 } 2476 } 2477 2478 assert(spe != NULL && spe->method() != NULL, ""); 2479 assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() && 2480 spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()), 2481 "MH intrinsic invariant"); 2482 return spe->method(); 2483 } 2484 2485 // Helper for unpacking the return value from linkMethod and linkCallSite. 2486 static methodHandle unpack_method_and_appendix(Handle mname, 2487 Klass* accessing_klass, 2488 objArrayHandle appendix_box, 2489 Handle* appendix_result, 2490 TRAPS) { 2491 methodHandle empty; 2492 if (mname.not_null()) { 2493 Method* m = java_lang_invoke_MemberName::vmtarget(mname()); 2494 if (m != NULL) { 2495 oop appendix = appendix_box->obj_at(0); 2496 if (TraceMethodHandles) { 2497 #ifndef PRODUCT 2498 ttyLocker ttyl; 2499 tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m)); 2500 m->print(); 2501 if (appendix != NULL) { tty->print("appendix = "); appendix->print(); } 2502 tty->cr(); 2503 #endif //PRODUCT 2504 } 2505 (*appendix_result) = Handle(THREAD, appendix); 2506 // the target is stored in the cpCache and if a reference to this 2507 // MethodName is dropped we need a way to make sure the 2508 // class_loader containing this method is kept alive. 2509 // FIXME: the appendix might also preserve this dependency. 2510 ClassLoaderData* this_key = accessing_klass->class_loader_data(); 2511 this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM 2512 return methodHandle(THREAD, m); 2513 } 2514 } 2515 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty); 2516 return empty; 2517 } 2518 2519 methodHandle SystemDictionary::find_method_handle_invoker(Klass* klass, 2520 Symbol* name, 2521 Symbol* signature, 2522 Klass* accessing_klass, 2523 Handle *appendix_result, 2524 Handle *method_type_result, 2525 TRAPS) { 2526 methodHandle empty; 2527 assert(THREAD->can_call_java() ,""); 2528 Handle method_type = 2529 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty)); 2530 2531 int ref_kind = JVM_REF_invokeVirtual; 2532 oop name_oop = StringTable::intern(name, CHECK_(empty)); 2533 Handle name_str (THREAD, name_oop); 2534 objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_(empty)); 2535 assert(appendix_box->obj_at(0) == NULL, ""); 2536 2537 // This should not happen. JDK code should take care of that. 2538 if (accessing_klass == NULL || method_type.is_null()) { 2539 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty); 2540 } 2541 2542 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName 2543 JavaCallArguments args; 2544 args.push_oop(Handle(THREAD, accessing_klass->java_mirror())); 2545 args.push_int(ref_kind); 2546 args.push_oop(Handle(THREAD, klass->java_mirror())); 2547 args.push_oop(name_str); 2548 args.push_oop(method_type); 2549 args.push_oop(appendix_box); 2550 JavaValue result(T_OBJECT); 2551 JavaCalls::call_static(&result, 2552 SystemDictionary::MethodHandleNatives_klass(), 2553 vmSymbols::linkMethod_name(), 2554 vmSymbols::linkMethod_signature(), 2555 &args, CHECK_(empty)); 2556 Handle mname(THREAD, (oop) result.get_jobject()); 2557 (*method_type_result) = method_type; 2558 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD); 2559 } 2560 2561 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks. 2562 // We must ensure that all class loaders everywhere will reach this class, for any client. 2563 // This is a safe bet for public classes in java.lang, such as Object and String. 2564 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types. 2565 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util. 2566 static bool is_always_visible_class(oop mirror) { 2567 Klass* klass = java_lang_Class::as_Klass(mirror); 2568 if (klass->is_objArray_klass()) { 2569 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type 2570 } 2571 if (klass->is_typeArray_klass()) { 2572 return true; // primitive array 2573 } 2574 assert(klass->is_instance_klass(), "%s", klass->external_name()); 2575 return klass->is_public() && 2576 (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) || // java.lang 2577 InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass())); // java.lang.invoke 2578 } 2579 2580 2581 // Return the Java mirror (java.lang.Class instance) for a single-character 2582 // descriptor. This result, when available, is the same as produced by the 2583 // heavier API point of the same name that takes a Symbol. 2584 oop SystemDictionary::find_java_mirror_for_type(char signature_char) { 2585 return java_lang_Class::primitive_mirror(char2type(signature_char)); 2586 } 2587 2588 // Find or construct the Java mirror (java.lang.Class instance) for a 2589 // for the given field type signature, as interpreted relative to the 2590 // given class loader. Handles primitives, void, references, arrays, 2591 // and all other reflectable types, except method types. 2592 // N.B. Code in reflection should use this entry point. 2593 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature, 2594 Klass* accessing_klass, 2595 Handle class_loader, 2596 Handle protection_domain, 2597 SignatureStream::FailureMode failure_mode, 2598 TRAPS) { 2599 Handle empty; 2600 2601 assert(accessing_klass == NULL || (class_loader.is_null() && protection_domain.is_null()), 2602 "one or the other, or perhaps neither"); 2603 2604 Symbol* type = signature; 2605 2606 // What we have here must be a valid field descriptor, 2607 // and all valid field descriptors are supported. 2608 // Produce the same java.lang.Class that reflection reports. 2609 if (type->utf8_length() == 1) { 2610 2611 // It's a primitive. (Void has a primitive mirror too.) 2612 char ch = (char) type->byte_at(0); 2613 assert(is_java_primitive(char2type(ch)) || ch == 'V', ""); 2614 return Handle(THREAD, find_java_mirror_for_type(ch)); 2615 2616 } else if (FieldType::is_obj(type) || FieldType::is_array(type)) { 2617 2618 // It's a reference type. 2619 if (accessing_klass != NULL) { 2620 class_loader = Handle(THREAD, accessing_klass->class_loader()); 2621 protection_domain = Handle(THREAD, accessing_klass->protection_domain()); 2622 } 2623 Klass* constant_type_klass; 2624 if (failure_mode == SignatureStream::ReturnNull) { 2625 constant_type_klass = resolve_or_null(type, class_loader, protection_domain, 2626 CHECK_(empty)); 2627 } else { 2628 bool throw_error = (failure_mode == SignatureStream::NCDFError); 2629 constant_type_klass = resolve_or_fail(type, class_loader, protection_domain, 2630 throw_error, CHECK_(empty)); 2631 } 2632 if (constant_type_klass == NULL) { 2633 return Handle(); // report failure this way 2634 } 2635 Handle mirror(THREAD, constant_type_klass->java_mirror()); 2636 2637 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve. 2638 if (accessing_klass != NULL) { 2639 Klass* sel_klass = constant_type_klass; 2640 bool fold_type_to_class = true; 2641 LinkResolver::check_klass_accessability(accessing_klass, sel_klass, 2642 fold_type_to_class, CHECK_(empty)); 2643 } 2644 2645 return mirror; 2646 2647 } 2648 2649 // Fall through to an error. 2650 assert(false, "unsupported mirror syntax"); 2651 THROW_MSG_(vmSymbols::java_lang_InternalError(), "unsupported mirror syntax", empty); 2652 } 2653 2654 2655 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given 2656 // signature, as interpreted relative to the given class loader. 2657 // Because of class loader constraints, all method handle usage must be 2658 // consistent with this loader. 2659 Handle SystemDictionary::find_method_handle_type(Symbol* signature, 2660 Klass* accessing_klass, 2661 TRAPS) { 2662 Handle empty; 2663 vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics 2664 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid); 2665 int index = invoke_method_table()->hash_to_index(hash); 2666 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid); 2667 if (spe != NULL && spe->method_type() != NULL) { 2668 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), ""); 2669 return Handle(THREAD, spe->method_type()); 2670 } else if (!THREAD->can_call_java()) { 2671 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME 2672 return Handle(); // do not attempt from within compiler, unless it was cached 2673 } 2674 2675 Handle class_loader, protection_domain; 2676 if (accessing_klass != NULL) { 2677 class_loader = Handle(THREAD, accessing_klass->class_loader()); 2678 protection_domain = Handle(THREAD, accessing_klass->protection_domain()); 2679 } 2680 bool can_be_cached = true; 2681 int npts = ArgumentCount(signature).size(); 2682 objArrayHandle pts = oopFactory::new_objArray_handle(SystemDictionary::Class_klass(), npts, CHECK_(empty)); 2683 int arg = 0; 2684 Handle rt; // the return type from the signature 2685 ResourceMark rm(THREAD); 2686 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) { 2687 oop mirror = NULL; 2688 if (can_be_cached) { 2689 // Use neutral class loader to lookup candidate classes to be placed in the cache. 2690 mirror = ss.as_java_mirror(Handle(), Handle(), 2691 SignatureStream::ReturnNull, CHECK_(empty)); 2692 if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) { 2693 // Fall back to accessing_klass context. 2694 can_be_cached = false; 2695 } 2696 } 2697 if (!can_be_cached) { 2698 // Resolve, throwing a real error if it doesn't work. 2699 mirror = ss.as_java_mirror(class_loader, protection_domain, 2700 SignatureStream::NCDFError, CHECK_(empty)); 2701 } 2702 assert(!oopDesc::is_null(mirror), "%s", ss.as_symbol(THREAD)->as_C_string()); 2703 if (ss.at_return_type()) 2704 rt = Handle(THREAD, mirror); 2705 else 2706 pts->obj_at_put(arg++, mirror); 2707 2708 // Check accessibility. 2709 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != NULL) { 2710 Klass* sel_klass = java_lang_Class::as_Klass(mirror); 2711 mirror = NULL; // safety 2712 // Emulate ConstantPool::verify_constant_pool_resolve. 2713 bool fold_type_to_class = true; 2714 LinkResolver::check_klass_accessability(accessing_klass, sel_klass, 2715 fold_type_to_class, CHECK_(empty)); 2716 } 2717 } 2718 assert(arg == npts, ""); 2719 2720 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType 2721 JavaCallArguments args(Handle(THREAD, rt())); 2722 args.push_oop(pts); 2723 JavaValue result(T_OBJECT); 2724 JavaCalls::call_static(&result, 2725 SystemDictionary::MethodHandleNatives_klass(), 2726 vmSymbols::findMethodHandleType_name(), 2727 vmSymbols::findMethodHandleType_signature(), 2728 &args, CHECK_(empty)); 2729 Handle method_type(THREAD, (oop) result.get_jobject()); 2730 2731 if (can_be_cached) { 2732 // We can cache this MethodType inside the JVM. 2733 MutexLocker ml(SystemDictionary_lock, THREAD); 2734 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid); 2735 if (spe == NULL) 2736 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid); 2737 if (spe->method_type() == NULL) { 2738 spe->set_method_type(method_type()); 2739 } 2740 } 2741 2742 // report back to the caller with the MethodType 2743 return method_type; 2744 } 2745 2746 Handle SystemDictionary::find_field_handle_type(Symbol* signature, 2747 Klass* accessing_klass, 2748 TRAPS) { 2749 Handle empty; 2750 ResourceMark rm(THREAD); 2751 SignatureStream ss(signature, /*is_method=*/ false); 2752 if (!ss.is_done()) { 2753 Handle class_loader, protection_domain; 2754 if (accessing_klass != NULL) { 2755 class_loader = Handle(THREAD, accessing_klass->class_loader()); 2756 protection_domain = Handle(THREAD, accessing_klass->protection_domain()); 2757 } 2758 oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty)); 2759 ss.next(); 2760 if (ss.is_done()) { 2761 return Handle(THREAD, mirror); 2762 } 2763 } 2764 return empty; 2765 } 2766 2767 // Ask Java code to find or construct a method handle constant. 2768 Handle SystemDictionary::link_method_handle_constant(Klass* caller, 2769 int ref_kind, //e.g., JVM_REF_invokeVirtual 2770 Klass* callee, 2771 Symbol* name, 2772 Symbol* signature, 2773 TRAPS) { 2774 Handle empty; 2775 if (caller == NULL) { 2776 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty); 2777 } 2778 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty)); 2779 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty)); 2780 2781 // Put symbolic info from the MH constant into freshly created MemberName and resolve it. 2782 Handle mname = MemberName_klass()->allocate_instance_handle(CHECK_(empty)); 2783 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror()); 2784 java_lang_invoke_MemberName::set_name (mname(), name_str()); 2785 java_lang_invoke_MemberName::set_type (mname(), signature_str()); 2786 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind)); 2787 2788 if (ref_kind == JVM_REF_invokeVirtual && 2789 callee->name() == vmSymbols::java_lang_invoke_MethodHandle() && 2790 (name == vmSymbols::invoke_name() || name == vmSymbols::invokeExact_name())) { 2791 // Skip resolution for j.l.i.MethodHandle.invoke()/invokeExact(). 2792 // They are public signature polymorphic methods, but require appendix argument 2793 // which MemberName resolution doesn't handle. There's special logic on JDK side to handle them 2794 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()). 2795 } else { 2796 MethodHandles::resolve_MemberName(mname, caller, CHECK_(empty)); 2797 } 2798 2799 // After method/field resolution succeeded, it's safe to resolve MH signature as well. 2800 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty)); 2801 2802 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle 2803 JavaCallArguments args; 2804 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class 2805 args.push_int(ref_kind); 2806 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class 2807 args.push_oop(name_str); 2808 args.push_oop(type); 2809 JavaValue result(T_OBJECT); 2810 JavaCalls::call_static(&result, 2811 SystemDictionary::MethodHandleNatives_klass(), 2812 vmSymbols::linkMethodHandleConstant_name(), 2813 vmSymbols::linkMethodHandleConstant_signature(), 2814 &args, CHECK_(empty)); 2815 return Handle(THREAD, (oop) result.get_jobject()); 2816 } 2817 2818 // Ask Java to compute a constant by invoking a BSM given a Dynamic_info CP entry 2819 Handle SystemDictionary::link_dynamic_constant(Klass* caller, 2820 int condy_index, 2821 Handle bootstrap_specifier, 2822 Symbol* name, 2823 Symbol* type, 2824 TRAPS) { 2825 Handle empty; 2826 Handle bsm, info; 2827 if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) { 2828 bsm = bootstrap_specifier; 2829 } else { 2830 assert(bootstrap_specifier->is_objArray(), ""); 2831 objArrayOop args = (objArrayOop) bootstrap_specifier(); 2832 assert(args->length() == 2, ""); 2833 bsm = Handle(THREAD, args->obj_at(0)); 2834 info = Handle(THREAD, args->obj_at(1)); 2835 } 2836 guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()), 2837 "caller must supply a valid BSM"); 2838 2839 // This should not happen. JDK code should take care of that. 2840 if (caller == NULL) { 2841 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad dynamic constant", empty); 2842 } 2843 2844 Handle constant_name = java_lang_String::create_from_symbol(name, CHECK_(empty)); 2845 2846 // Resolve the constant type in the context of the caller class 2847 Handle type_mirror = find_java_mirror_for_type(type, caller, SignatureStream::NCDFError, 2848 CHECK_(empty)); 2849 2850 // call java.lang.invoke.MethodHandleNatives::linkConstantDyanmic(caller, condy_index, bsm, type, info) 2851 JavaCallArguments args; 2852 args.push_oop(Handle(THREAD, caller->java_mirror())); 2853 args.push_int(condy_index); 2854 args.push_oop(bsm); 2855 args.push_oop(constant_name); 2856 args.push_oop(type_mirror); 2857 args.push_oop(info); 2858 JavaValue result(T_OBJECT); 2859 JavaCalls::call_static(&result, 2860 SystemDictionary::MethodHandleNatives_klass(), 2861 vmSymbols::linkDynamicConstant_name(), 2862 vmSymbols::linkDynamicConstant_signature(), 2863 &args, CHECK_(empty)); 2864 2865 return Handle(THREAD, (oop) result.get_jobject()); 2866 } 2867 2868 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given 2869 // name and signature, as interpreted relative to the given class loader. 2870 methodHandle SystemDictionary::find_dynamic_call_site_invoker(Klass* caller, 2871 int indy_index, 2872 Handle bootstrap_specifier, 2873 Symbol* name, 2874 Symbol* type, 2875 Handle *appendix_result, 2876 Handle *method_type_result, 2877 TRAPS) { 2878 methodHandle empty; 2879 Handle bsm, info; 2880 if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) { 2881 bsm = bootstrap_specifier; 2882 } else { 2883 objArrayOop args = (objArrayOop) bootstrap_specifier(); 2884 assert(args->length() == 2, ""); 2885 bsm = Handle(THREAD, args->obj_at(0)); 2886 info = Handle(THREAD, args->obj_at(1)); 2887 } 2888 guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()), 2889 "caller must supply a valid BSM"); 2890 2891 Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty)); 2892 Handle method_type = find_method_handle_type(type, caller, CHECK_(empty)); 2893 2894 // This should not happen. JDK code should take care of that. 2895 if (caller == NULL || method_type.is_null()) { 2896 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty); 2897 } 2898 2899 objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_(empty)); 2900 assert(appendix_box->obj_at(0) == NULL, ""); 2901 2902 // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, indy_index, bsm, name, mtype, info, &appendix) 2903 JavaCallArguments args; 2904 args.push_oop(Handle(THREAD, caller->java_mirror())); 2905 args.push_int(indy_index); 2906 args.push_oop(bsm); 2907 args.push_oop(method_name); 2908 args.push_oop(method_type); 2909 args.push_oop(info); 2910 args.push_oop(appendix_box); 2911 JavaValue result(T_OBJECT); 2912 JavaCalls::call_static(&result, 2913 SystemDictionary::MethodHandleNatives_klass(), 2914 vmSymbols::linkCallSite_name(), 2915 vmSymbols::linkCallSite_signature(), 2916 &args, CHECK_(empty)); 2917 Handle mname(THREAD, (oop) result.get_jobject()); 2918 (*method_type_result) = method_type; 2919 return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD); 2920 } 2921 2922 // Protection domain cache table handling 2923 2924 ProtectionDomainCacheEntry* SystemDictionary::cache_get(Handle protection_domain) { 2925 return _pd_cache_table->get(protection_domain); 2926 } 2927 2928 #if INCLUDE_CDS 2929 void SystemDictionary::reorder_dictionary_for_sharing() { 2930 ClassLoaderData::the_null_class_loader_data()->dictionary()->reorder_dictionary_for_sharing(); 2931 } 2932 #endif 2933 2934 size_t SystemDictionary::count_bytes_for_buckets() { 2935 return ClassLoaderData::the_null_class_loader_data()->dictionary()->count_bytes_for_buckets(); 2936 } 2937 2938 size_t SystemDictionary::count_bytes_for_table() { 2939 return ClassLoaderData::the_null_class_loader_data()->dictionary()->count_bytes_for_table(); 2940 } 2941 2942 void SystemDictionary::copy_buckets(char* top, char* end) { 2943 ClassLoaderData::the_null_class_loader_data()->dictionary()->copy_buckets(top, end); 2944 } 2945 2946 void SystemDictionary::copy_table(char* top, char* end) { 2947 ClassLoaderData::the_null_class_loader_data()->dictionary()->copy_table(top, end); 2948 } 2949 2950 // ---------------------------------------------------------------------------- 2951 void SystemDictionary::print_shared(outputStream *st) { 2952 shared_dictionary()->print_on(st); 2953 } 2954 2955 void SystemDictionary::print_on(outputStream *st) { 2956 if (shared_dictionary() != NULL) { 2957 st->print_cr("Shared Dictionary"); 2958 shared_dictionary()->print_on(st); 2959 st->cr(); 2960 } 2961 2962 GCMutexLocker mu(SystemDictionary_lock); 2963 2964 ClassLoaderDataGraph::print_dictionary(st); 2965 2966 // Placeholders 2967 placeholders()->print_on(st); 2968 st->cr(); 2969 2970 // loader constraints - print under SD_lock 2971 constraints()->print_on(st); 2972 st->cr(); 2973 2974 _pd_cache_table->print_on(st); 2975 st->cr(); 2976 } 2977 2978 void SystemDictionary::verify() { 2979 guarantee(constraints() != NULL, 2980 "Verify of loader constraints failed"); 2981 guarantee(placeholders()->number_of_entries() >= 0, 2982 "Verify of placeholders failed"); 2983 2984 GCMutexLocker mu(SystemDictionary_lock); 2985 2986 // Verify dictionary 2987 ClassLoaderDataGraph::verify_dictionary(); 2988 2989 placeholders()->verify(); 2990 2991 // Verify constraint table 2992 guarantee(constraints() != NULL, "Verify of loader constraints failed"); 2993 constraints()->verify(placeholders()); 2994 2995 _pd_cache_table->verify(); 2996 } 2997 2998 void SystemDictionary::dump(outputStream *st, bool verbose) { 2999 assert_locked_or_safepoint(SystemDictionary_lock); 3000 if (verbose) { 3001 print_on(st); 3002 } else { 3003 if (shared_dictionary() != NULL) { 3004 shared_dictionary()->print_table_statistics(st, "Shared Dictionary"); 3005 } 3006 ClassLoaderDataGraph::print_dictionary_statistics(st); 3007 placeholders()->print_table_statistics(st, "Placeholder Table"); 3008 constraints()->print_table_statistics(st, "LoaderConstraints Table"); 3009 _pd_cache_table->print_table_statistics(st, "ProtectionDomainCache Table"); 3010 } 3011 } 3012 3013 // Utility for dumping dictionaries. 3014 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) : 3015 DCmdWithParser(output, heap), 3016 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders", 3017 "BOOLEAN", false, "false") { 3018 _dcmdparser.add_dcmd_option(&_verbose); 3019 } 3020 3021 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) { 3022 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict, 3023 _verbose.value()); 3024 VMThread::execute(&dumper); 3025 } 3026 3027 int SystemDictionaryDCmd::num_arguments() { 3028 ResourceMark rm; 3029 SystemDictionaryDCmd* dcmd = new SystemDictionaryDCmd(NULL, false); 3030 if (dcmd != NULL) { 3031 DCmdMark mark(dcmd); 3032 return dcmd->_dcmdparser.num_arguments(); 3033 } else { 3034 return 0; 3035 } 3036 } 3037 3038 class CombineDictionariesClosure : public CLDClosure { 3039 private: 3040 Dictionary* _master_dictionary; 3041 public: 3042 CombineDictionariesClosure(Dictionary* master_dictionary) : 3043 _master_dictionary(master_dictionary) {} 3044 void do_cld(ClassLoaderData* cld) { 3045 ResourceMark rm; 3046 if (cld->is_system_class_loader_data() || cld->is_platform_class_loader_data()) { 3047 for (int i = 0; i < cld->dictionary()->table_size(); ++i) { 3048 Dictionary* curr_dictionary = cld->dictionary(); 3049 DictionaryEntry* p = curr_dictionary->bucket(i); 3050 while (p != NULL) { 3051 Symbol* name = p->instance_klass()->name(); 3052 unsigned int d_hash = _master_dictionary->compute_hash(name); 3053 int d_index = _master_dictionary->hash_to_index(d_hash); 3054 DictionaryEntry* next = p->next(); 3055 if (p->literal()->class_loader_data() != cld) { 3056 // This is an initiating class loader entry; don't use it 3057 log_trace(cds)("Skipping initiating cl entry: %s", name->as_C_string()); 3058 curr_dictionary->free_entry(p); 3059 } else { 3060 log_trace(cds)("Moved to boot dictionary: %s", name->as_C_string()); 3061 curr_dictionary->unlink_entry(p); 3062 p->set_pd_set(NULL); // pd_set is runtime only information and will be reconstructed. 3063 _master_dictionary->add_entry(d_index, p); 3064 } 3065 p = next; 3066 } 3067 *curr_dictionary->bucket_addr(i) = NULL; 3068 } 3069 } 3070 } 3071 }; 3072 3073 // Combining platform and system loader dictionaries into boot loader dictionary. 3074 // During run time, we only have one shared dictionary. 3075 void SystemDictionary::combine_shared_dictionaries() { 3076 assert(DumpSharedSpaces, "dump time only"); 3077 // If AppCDS isn't enabled, we only dump the classes in the boot loader dictionary 3078 // into the shared archive. 3079 if (UseAppCDS) { 3080 Dictionary* master_dictionary = ClassLoaderData::the_null_class_loader_data()->dictionary(); 3081 CombineDictionariesClosure cdc(master_dictionary); 3082 ClassLoaderDataGraph::cld_do(&cdc); 3083 } 3084 3085 // These tables are no longer valid or necessary. Keeping them around will 3086 // cause SystemDictionary::verify() to fail. Let's empty them. 3087 _placeholders = new PlaceholderTable(_placeholder_table_size); 3088 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size); 3089 3090 NOT_PRODUCT(SystemDictionary::verify()); 3091 } 3092 3093 // caller needs ResourceMark 3094 const char* SystemDictionary::loader_name(const oop loader) { 3095 return ((loader) == NULL ? "<bootloader>" : 3096 InstanceKlass::cast((loader)->klass())->name()->as_C_string()); 3097 } 3098 3099 // caller needs ResourceMark 3100 const char* SystemDictionary::loader_name(const ClassLoaderData* loader_data) { 3101 return (loader_data->class_loader() == NULL ? "<bootloader>" : 3102 SystemDictionary::loader_name(loader_data->class_loader())); 3103 }